I really enjoyed the show (I was there on Tuesday) I think if I'd gone on Monday, I probably would've come back for the Tuesday show as well.
I wasn't all that familiar beforehand with Jonsi's music, but found it really engaging. The visuals were impressive and meshed well with the music. Overall, the crowd was very reverent and quiet -- it's possible that the Monday crowd Sweetcell describes might have been even quieter, but I thought the Tuesday crowd was pretty good in that respect (especially considering how often quiet shows are marred by people talking).
The atmosphere was magical. I hope Jonsi comes back to the club. Oh, and if his music isn't already being used in film soundtracks, it should be -- it was very evocative.