Yes, you need to read any authors work to understand them. The entry on Aristotle's logic in the Standford Encyclopedia of Philosophy is as good a synopsis as any.
You could do well to read more than one translation - short of becoming a scholar on ancient Greek if you seek to understand what Aristotle thought. Consider, tho that he did not write much of what is attributed to him:
The great body of Aristotle's thought that has come down to us is in the form of "treatise" on various subjects, such as logic, physics, ethics, psychology, biology, and politics. It seems that these treatise began as notes on (or summaries of) Aristotle's lectures at the Lyceum in Athens. He continued to edit and revise them throughout his life, as his views evolved, but never brought them to a state of completion for publication. Subsequently they were edited and organized into "books" by his students, and then the whole corpus was transmitted through a series of transcribers, translators, and commentators.
And essentially what you are "understanding" is what is commonly accepted as Aristotle's writings. Not quite a "John Frum" experience, but it is worth pointing out that as well, the writings of Aristotle have been interpreted as well translated between Greek, Arabic, Latin and English.
The story of how Aristotle came to be considered the prime authority on matters of reason ("the master of those who know") is interesting. His writings certainly didn't have such a commanding status in his own time, nor at any later time in the ancient world. Even following the collapse of ancient civilization in around 500 AD, the only work of Aristotle known in the west was a Latin translation (by Boethius) of his treatise on logic. Not until the twelfth century did scholars in western Europe begin to gain access to the full range of Aristotle's treatise, and even then they did not acquire the actual Greek texts. Aristotle's teachings had survived in various scholarly communities in the east, such as among the Syrians, and these works were acquired by the Arabs when they conquered Syria around 650 AD. Eventually the works of Aristotle, along with the commentaries of Arab scholars, spread throughout the Islamic world. Beginning with the re-conquest of Toledo in 1085 and Sicily in 1091, western scholars (such as Gerard of Cremona, d. 1187) began to encounter these works and translate them into Latin. The structure of the Arab language is quite different from Greek and Latin (which are fairly similar to each other), so there was unavoidable paraphrasing in the passage from the original Greek to Arabic, and then again in the translation from Arabic to Latin. In effect, the first exposure to the full extent of Aristotle's writings came in the form of Latin paraphrases of Arab paraphrases of (and commentaries on) Syriac paraphrases of second-hand copies of the original Greek texts. Not surprisingly, the resulting Latin renderings were somewhat unreliable.
It is likely tho enough to appreciate the differences one may encounter from alternative translations. For example:
...today we often find Aristotle cited, especially in the sciences, as an example of erroneous thinking.
Nevertheless, the works of Aristotle are, if nothing else, a very interesting record of the attempts of one (obviously very intelligent) man to understand and systematize a wide range of knowledge on the basis of primitive principles and perceptions. For example, Books V and VI of Aristotle's Physics presents an interesting argument that space, time, and motion must all be continuous rather than discrete (atomistic). The argument relies on a number of definitions, most crucially on the definition of the word "between". This also gives a good illustration of the challenges that a scholar faces when trying to determine, first, exactly what Aristotle wrote, and second, exactly what he meant. Two of the most widely-available English translations of Aristotle's Physics are the Loeb Classic Library version by Wicksteed and Cornford (W&C), and another translation by Hardie and Gaye (H&G). Below is the renderings of Aristotle's definition of "between" contained in H&G:
That which a changing thing, if it changes continuously in a natural manner, naturally reaches before it reaches that to which it changes last, is between. Thus 'between' implies the presence of at least three things: for in a process of change it is the contrary that is 'last': and a thing is moved continuously if it leaves no gap or only the smallest possible gap in the material-not in the time (for a gap in the time does not prevent things having a 'between', while, on the other hand, there is nothing to prevent the highest note sounding immediately after the lowest) but in the material in which the motion takes place. This is manifestly true not only in local changes but in every other kind as well. (Now every change implies a pair of opposites, and opposites may be either contraries or contradictories; since then contradiction admits of no mean term, it is obvious that 'between' must imply a pair of contraries) That is locally contrary which is most distant in a straight line: for the shortest line is definitely limited, and that which is definitely limited constitutes a measure.
Compare this with the same passage in the W&C translation:
Since all change is between opposites, and opposites are either contraries or contradictories, and there is nothing between contradictories, it is clear that the intermediate or "between" can only exist when there are two contraries. B is between A and C if anything passing (locally or otherwise) by a continuous change in accordance with its nature must necessarily come to B before it reaches the extreme C on its way thereto from A. 'Between' implies at least three terms: the 'whence' of the passing, the opposite of the whence, namely the 'whither', and something on the line of passage, nearer to the whence than the whither is; and the passage is continuous if there is no break or leap in the course - or, if any, only the minimum. I am speaking of a break, not in time, but in that with respect to which the changing thing is changing; for in time the bottom note of the diapason may be followed by the top note (which constitutes the maximum possible break or leap in the scale) just as immediately as any two notes severed by the smallest conceivable interval. All which applies not only to changes of place but the other kinds of change as well. In the local application of the word, one thing is the contrary of another, if it is farther from it, in a straight line, than any other individual thing of the same order in the field under consideration. The straight line is chosen because, as the shortest, it is the only definite one between any two positions, and a measure or standard must be definite.
Notice that the first sentence in W&C ("Since all change is between opposites...") does not appear in the R&H translation until near the end, and then only parenthetically ("Now every change implies a pair of opposites..."). Also, W&C avail themselves of symbolic characters A, B, C, whereas these do not appear at all R&H's strictly verbal rendering. Throughout there are major differences in syntax, sentence structure, and vocabulary. This shows why we should always be cautious when quoting "what Aristotle said". Obviously it's not possible to directly transliterate from the ancient Greek to modern English, so at best a translator can only hope to convey the correct sense of what Aristotle was trying to say.
All that said, "Aristotle's philosophy" is no different than anyone else's philosophy as philosophy is "love of wisdom" (read: respect for obtaining knowledge) and philosophy is neither a matter of personal outlook nor a way of looking at things (the world, the case, states of affairs, what is). It is, in fact, misnomer to use the word philosophy to describe a view of what is, beliefs, credo, ideology, a school of thought, a way of looking at things or any "-ism". Love of wisdom requires knowledge, not opinion, sentiment, personal view, etc. Do you need to read the Organon to understand philosophy? No. Do you need to read the Organon to understand Aristotle? Yes.