This is what I've been worried about for a while now, ever since one of the later trailers came out. Sadly my fears were backed up upon release by numerous reviews confirming my suspicions.
I'm still going to see it, and I'm really hoping I like it. I'm just going in with low expectations.
Y'know what I hate? People who base their expectations solely on a few reviews they read.
Rotten Tomatoes says 66% of reviewers gave it a positive review; even assuming reviewers are in touch with what the general population likes from a movie (they're normally wrong), that's a 2/3 chance you'll at least enjoy it.
Considering where it's coming from, yeah, pretty likely to be a disappointment from Casino Royale, but take it on its own merits and enjoy it as its own film, and it should be pretty fun.
From what I hear, these Bond films have been planned as a three-movie arc; in that way, this is the "Empire Strikes Back" of the trilogy; the middle film is bound to be the weakest.