It's something you have to see through to the end to really appreciate. Especially after book 5, HoC, you havent even met all the characters or seen major plot points... which is totally insane but true. I understand why people burn out, but some of those critiques ring particularly hollow. I've know plenty of people personally who read about half of tdtcb and give similar critiques, and it's equally ridiculous, imo. It's difficult to truely grasp the depth of tdtcb until you've finished the series and then go back and read it again.
Each is entitled to his own opinion, and books like Malazan and TSA aren't for everyone. Too long, too boring, slow, too many characters... I can see and understand all these criticisms, and many more. That said, calling it shallow and underdeveloped is commical. The plot is complex and convuluted, and of course things seem like they just happen for no reason when you don't see where they end up. There are plenty of inconsistencies and plot holes, stories half told and things unexplained, and that can be really irritating, but the depth and development are there if you look for it.
As much of a fan I am of Bakker, I'd put Erikson as a close second, and generally for all the same reasons.