My group got there last Friday night and had some different experiences than you did, perhaps because we started at the bottom of the park (after eating at the feast) and break times scattered around, but with the exception of Backwoods and Club Blood, we didn't feel they were underpopulated at all. From our path around the park:
MHH was quite good and I liked the extra rooms built since last year. This was also the first time we got to experience the elevator part. I suspect the plans were done by someone with no experience with heavy crowds since people get backed up at that point a lot until they flush people through. But agreed, great length and good scenes. The actors also seemed to be comfortable using the hallways well to surprise people multiple times.
We headed over to Death Trap and two of us got to enjoy a "guided tour" with an enthusiastic Mastermind and it was well populated, though most of the group couldn't hear him because he started speaking so quickly with each room (but it was pretty awesome).
Age of Darkness by the bathrooms where Death Trap let out was well populated and people were really in character with a jester who tried making rhyming poems at people (credit for decent ones while going off the cuff there. She tried hard!), and they teamed up against a few people while we were there. Due to the design, though, we were surprised to be told no pictures there. The costumes are really good, and the medieval theme looked good when the knight and the queen chased after a girl near us.
Grave Walkers is a great concept that I liked a lot. A scarezone with a maze part once you move through with lots of neat spots and really great actors. The rains on Saturday didn't stop them from writhing around and going after people then too.
Backwoods was disappointing. The concept is still really good, but somehow the actors were lackluster the two times we went through. I think they need to rethink the path and hiding spots better. Agreed that the paths are just too wide. It's almost as bad as the haunts at Great Adventure where the actors have to run a half mile just to get to you. Not good for scares or the actors.
Asylum had the longest lines and is still very well done. Moving the electric chair here was smart, but changing the timing to go off every 30 seconds got old really fast.
Terror Square was much better than last year. Shorter with less dead space and good use of the scenery. The lead (I think - the big guy who looks like the sheriff) is enthusiastic. The noise from Demon Drop and the longer walk makes it kind of out of the way and less effective. A shame as the crew did a great job, but the lines just did not get very long.
Cornstalkers was still good despite being one of the oldest mazes. The tighter paths were fantastic, and many scarecrows/burlap covered actors did a great job of using unexpected spots.
Club Blood feels tired now. At least only a few actors did a good job of scaring people. The dancers and dj just were kind of there, which made the turnaround at the back of the building seem like a boring waste with the dead space and that long pathway of plastic sheets. There really was a lot of dead space this time and felt short. Needs to be rethought, especially since the vampire club theme wasn't that bad in previous years.
Psycho Circus was really underpopulated when we went. There are a few actors I think we remembered from last year who do a good job, but they were early in the maze or outside entertaining the line. The maze needs some refreshing here too. It would sell more 3d glasses with a better effort inside.
Cutthroat Island was lots of fun. I'm still curious what was used for the canon fire, but a nice mix of mermaid decoys and actors running around and scaring people. They used the fog pretty well, and the ship is truly amazing to look at in daylight as well as in fog.
For the shows:
Eternal Jamnation started off badly but got better. I've felt the crew are talented, but have had trouble in the past with doing something cohesive. The sound people also really overpowered things with the mikes so the sound felt distorted the past few years. After the first 3 songs, the show was pretty enjoyable. Perhaps moving away from the vampire theme helped too.
Harley Newman...nothing really out there to me, though the straitjacket bit was really good. Maybe I've just been desensitized from Jackass stunts in the past, but nothing else was really that memorable to me.
Cast in Bronze was a refreshing surprise. The concept is clever and unique and the musician is really talented. It was also a very nice break between lines. I hope they bring him back!