I've been here 5 times or so. The actual tank experience is a little trippy, though mostly just relaxing. I never hallucinated, just saw some strange colors, but nothing more than when I wake up in the middle of the night occassionally.
I think I got kind of bored so I LOVE that I can plug my iPhone in now. The last few times I used a guided meditation by Sam Harris and that was helpful. Of course, he mentions opening your eyes and sitting and whatnot.
The staff is really friendly and I've never had a bad experience with them.