I didn't like Chamber of Trials at all. The puzzles were either illogical, very easy, or downright odd. The graphical side of it was terrible and there was little actual gameplay to speak of. I found the custom music was poorly chosen as well.
Honestly I didn't like any of the levels in the third party pack; I suppose that since they were made in such small timeframes by inexperienced authors, and KS was in its infancy, you can't really expect them to be that good. (Of course, even today, the vast majority of levels pale terribly in comparison to the official levels. And those days when every month or so would be graced with such a fabulous work as The Life Ruby or A Walk At Night seem to be long gone. Oh man, you guys remember Demon Contract? I'm still hoping to see that one. I think my favorite screenshot was the one with the waterfall. I tried to draw a waterfall for this new level I'm making, but I didn't do very well. I'm going to have to try again. Waterfalls are hard to draw. Almost as bad as trees. Man, I hate drawing trees. I can't stand it. You know that tileset that was nothing but about five large, detailed trees? I wish I could draw trees like that.)
On the other hand, Underwater Adventure remains one of my all-time favorite levels.