Ill touch on what others have said and add a few things.
There is both a subjective and objective component to judging the Sebenza. Some people dont like how it feels in their hand, though many do, some people arent crazy about the thumbstud design, some like it a lot, so with these sorts of subjective issues, what it comes down to is a matter of taste and whether the knife feels good to YOU.
However, objectively, i dont think ANYONE will step forward and say its not a well made, very solid knife. So, its pretty much a given that the knife is of very high quality. I honestly cant recall anyone, not even the most vocal Sebenza bashers, claiming the knife isnt a very well made knife, and thats sort of remarkable if you think about it, even its haters grudgingly admit its a high quality knife and base their dislike on either what they feel is too high a price, or ergonomics, which is fine, to each his own.
Whether the knife feels right to you, and whether you think the superior quality justifies the higher price is up to you.
[Warning, what is written below is an opinion and not fact]
Personally, in terms of strength, design, fit and finish, i think it is truly one of the best made folders available, and that includes most custom knives i have examined. I have never once seen a Sebenza with any type of flaw. In my experience, and I have examined probably at least 100 of them, they are remarkably consistant knife to knife and i have yet to see a single one with any sort of defect or flaw in fit or finish, and thats something i just cannot say about any other production knife, and i have seen far too many custom knives that were not as well put together as a Sebenza. If Chris Reeve can have no blade play EVERY time, so should a $500-$600 custom, if CR can center the blade perfectly EVERY time, so should a $500 custom, if CR can make sure the lock is perfectly fitted to the blade EVERY time, so should a $500 custom, and yet, I have seen an awful lot of customs that were failing in one or several of these areas. Some of these makers are well known and popular.
Microtech has pretty decent fit and finish, though not perfect, i HAVE seen several that slipped by QC. Benchmade, well, let's just say, MT and CR are definitely a cut above, as they should be, at their higher respective prices.
I think that with the Sebenza, as is the case with many things in life, you have diminishing returns. What i mean is, yes, the Sebenza does cost quite a bit more than a Benchmade, and the Benchmade is not a bad knife, but, as is usually the case, you pay a disproportionately high amount to get that last little bit of quality, so, you pay maybe 100% more to get something that may only be 10% better, but thats always the case when buying very high-end products. Whether that last little bit of quality is worth a lot more $ to you, is, well, up to you.