I've been to see it twice now and have pretty much the same opinion as Brinniel. Gollum, the Black Riders, Shelob - all fantastically done. The Elves hand movements - incredibly irritating.
Ah the orcs, there's a subject of debate. Alright, if you're watching a video I suspect the pogosticks do look silly, but when you're there and they're flinging themselves around Saruman and after the Fellowship it works very well. In addition, when they come out into the audience and flippin' well terrify you it really, really works. Trust me. My name is Kath and I have been terrorised by an orc.
As for the music. Well, clearly I can't speak for all but I enjoyed it. The voices were fantastic for the Elves and the hobbits were just the right mix of good voices but relying on the acting to get the point across. The woman playing Galadriel had a beautiful voice and when she was singing Lothlorien the audience was just spellbound.
I didn't mind the mixing of Rohan and Gondor into one because it takes out all the going one way and then back and then another and back and then another. It worked. Cuts out confusion, especially for any theatre-goers who didn't know the story.
All in all I have to say I loved it and would happily go again. I may well!