I just finished running the module for a group of four adventurers (Human Paladin, Human Warlock, Human Fighter, Elf Cleric) and they managed to survive all the encounters. Analysis below:
[sblock]The toughest fight was definitely the statues, by far. The statues managed to knock down the fighter and keep him down, continuously pummelling him. The paladin, tanking the other statue, never got knocked down and had a relatively easy time fighting his. I can see why the recommended pre-gens have two fighters, since this fight would be brutal without a pair of tanks. Most of the daily powers were blown here.
Since the Paladin of Bahamut was very conscientious towards the wishes of the spirit, it was friendly by the time they confronted the elf. Helvec and his skeletons went down with ease. The final fight feels nicely climactic even at the easiest difficulty, with a good part of that coming from the elevated platform (and the challenge of actually getting up to the elf).
The hobgoblin fight was a lot of fun, especially with the traps. Our figher and paladin wound up fighting the hobgoblins while standing waist-deep in an oil-filled sarcophagus after they pulled the lantern off the top then jumped up.
As predicted, the riddle was challenging. It took hint 2 for someone to figure it out, and I had to stress the alcoves with the little statues a few times to call attention to them. Since I'll be running with younger players, in all likelihood, I will be tailoring this encounter to have a slightly less obtuse riddle.[/sblock]
Overall, I like it. This should be a fun module to run on game day!