Truth be told all these people are lying. The hate the New Jedi Order because Chewbacca dies in the first Book, and Anakin Solo dies in the tenth book. And they resent the EU writers for killing of a real and an EU Character - even though it was long past time for the to do it.
People don't say that, though. And people who pass judgement on NJO based on the first book, or even (I would say) on the first ten haven't really had much of the NJO experiances.
I think the NJO did alot of things well. It started a general plot line that all the books continued - instead of one enemy defeated per book there was one enemy for a whole series. The good guys started to lose - I love the Heros, but having them win all the time in the same way was getting WAY past old. The good guys started to DIE - and then had to explore how the CHARACTERS felt about that (Han Solo refers to it as the invisible bubble protecting his family from harm popped - watching his evolution through the NJO series is perhaps the most fun part). You also get to see where old heroes like Admiral Ackbar and Wedge Antilles end up. And it explores a bit more of the Baron Fel situation - you actually see his Son, Wedge Antilles Nephew, fall in love with Jaina Solo (who forms her own squadron by the way).
The later books in the NJO series are definatly the better ones. The characters and enemies have evolved enough that people understand both. And the battles are much grander, and much more intriguing. All in all I think the NJO series unified the Star Wars Authors and had them working towards a common goal again, which I like. But that's just my opionion. As you can see, most people didn't like the books.