Went to the 12:01 showing last night because I live in the States and couldn't wait any longer. I read a review this morning that complained about there being too many simultaneous plots (seven, to be exact), encumbering the film with too much weight to allow sufficient development of any of the characters. It's a common complaint with comic book movies (the X-Men movies took heat for it, and the Joel Schumacher Batman movies deserved it), and I figure it's a natural consequence of the differences inherent to the media of comics and film. It applies, but is forgivable here.
For what it's worth, I would rate my enjoyment of IM2 only slightly below that of its predecessor. The multiple plot lines were not a turn-off to me, though I agree they hampered development somewhat. My only problem with replacing Terrence Howard with Don Cheadle is a cynical expectation that, somewhere, someone will choose to see a "Y'all look alike" message and get their knickers in a twist. Johansson was delicious, Rockwell's Hammer was obsequious and oblivious (until very late), Rourke was too easily defeated (twice - though another 20-30 minutes would definitely have been overkill), and the "Ex-Wife" was hilarious. Actually, in a painful way, so is the Hammer suit-prototype seen at the Senate hearing... Probably won't see any Oscar nods, but plenty of nerdgasm to go around.