So first, a little bit about myself. I went to GenCon with family this year. I had gone to TD once before, and was admittedly somewhat soured on it - the final boss of my previous run was a huge dragon that wiped us in a few turns, and it made the rest of the dungeon feel somewhat pointless. I was told later that most people felt the boss was overtuned and that it usually isn't that bad, so I was willing to give the game another shot... and I'm glad I did! The other two people I was with, my mom and brother, were completely new to TD. It seemed like the rest of our group was also relatively new, some had gone once or twice but no real veterans. Anyway, we went in with me as a wizard, my brother as a fighter, and mom as the bard.
Some general feedback. First, as the Wizard, memorizing the planes was pretty neat. Unfortunately, there seems to be some confusion over just how it's supposed to work; the coach and one of the room DMs told me "find X" on the chart, and had me point at the correct plane, while the other two DMs I cast a spell with instead pointed at a plane and asked "What is this?"
The other general note is that there is a lot of noise. My mother, sadly, is somewhat hearing impaired (entirely deaf in one ear), and understanding what was going on when she has only one ear to listen with and has a hard time filtering out background noise was making the run a lot less enjoyable. Perhaps some way for someone who's hearing impaired can get a "read along script" would be a good idea.
Finally, this might just be our group being new-ish to the game and not knowing how to do combat efficiently yet, but it felt like it took too long to kill monsters and we didn't actually kill any of them. Perhaps a bit less health on monsters would be better?
Anyway, specific room feedback (we did the Underdark puzzle dungeon):
Elevator room: Loved it. There was some minor confusion over when we had to put the crystal in the first slot (whether it should be immediately after we flip the switch, or when the recording makes a ding to indicate the timer starting), but I think the DM was lenient enough with it to make it not matter. Beyond that though, I think it was an excellent way to start off the dungeon and make it clear that teamwork was necessary.
Carrion crawler fight: The special effects were neat, but I didn't see anything special happening with the room beyond the combat, aside from not wanting to hit the stalactite on the board.
Lava room: This was actually pretty frustrating. We didn't get the clue, but I don't think it would have helped us at all. Some more indication of how to actually solve the puzzle would have been good; the only way we figured it out was the DM stressing that the people who fell into the lava trying it at random were the second/third/etc people to cross. Overall, neat idea, but poor execution and the puzzle needed some kind of hint beyond blind guessing.
Fire serpent fight: This was pretty neat effects, but the spring water clue was given to us way too late to be of much use. I'm not sure if that was because our group was too slow at combat and didn't get past enough rounds fast enough, or because our half-deaf bard was more or less told to sing and didn't know to do much else.
Mushroom room: I'd personally like to see a script for the mushrooms, because while I think the puzzle was done well, they were hard as heck to hear properly. I think it was a combination of surrounding noise and garbled speakers. I can understand if the point of the puzzle was that you couldn't just hear every mushroom speak on demand, and had limited time to read each clue (and thus needed teamwork to split up and hear each mushroom and repeat what they said), but perhaps some mechanism that would show what they were saying while they were speaking, hiding it again until they spoke again when they finished, would be better. Also, there was some confusion over just what was going to happen in the room, with a few of us thinking we had to ask the mushrooms a question in order to figure out the puzzle.
Spider combat: Again, neat effects, but I really don't have much feedback for combat. I heard elsewhere that there was supposed to be a bard lore hint from the fight, but we never saw it if there was supposed to be one - again, not sure if that was because our group wasn't fast enough, because our bard couldn't hear what was happening, or just the GM not asking soon enough.
Final puzzle: This was really neat, but I think we ended up brute forcing the puzzle once we figured out it was a matter of timing and didn't need to get it 100% on the first try. I found out later that you're not supposed to get treasure if you have to brute force a room, so I'm not sure if we were supposed to get the treasure or if we would have lost it if we failed more. The DM here didn't seem to be fully attentive on the spiders though, which ticked my brother off when he got "called out" for letting a spider crawl on his hand after he had seen several others do the same thing and not get bitten. Beyond the possibly too lax DM though, I thought the puzzle was interesting, though we didn't figure out the clues from the houses at all.