As a born-and-raised Trekkie, I am excited to see the upcoming Star Trek film, but I'm also incredibly dubious now that we pretty much know who the entire cast is, with the exception of Captain Pike.
First off, the casting puts the makeup department at something of a disadvantage, for the most part. Allow me to show you the actors, and pictures of their 60's counterparts.
Captain Kirk:

(William Shatner, Chris Pine)
Spock:

(Leonard Nimoy, Zachary Quinto)
McCoy:

(DeForest Kelley, Karl Urban)
Sulu:

(George Takei, John Cho)
Scotty:

(James Doohan, Simon Pegg)
Uhura:

(Nichelle Nichols, Zoe Saldana)
Chekov:

(Walter Koenig, Anton Yelchin)
Now then... good matches? Eh, I think they're all right. There's only so close that a person can look. But there are several points upon which I am dubious:
1. I'm a big fan of Karl Urban, have been ever since Lord of the Rings. But... I just don't see him as Bones.
2. Is Chris Pine going to imitate Shatner's unique style of delivering dialogue? If not... gosh, that doesn't seem right, but how do you act like Shatner without bordering parody?
3. Simon Pegg. Mmkay then. I will give him the benefit of the doubt.
4. Plot, anyone? I understand the desire to keep it under wraps, but at the same time, going back to the Academy years of the crew of the Enterprise (as some rumors have said) seems a bit corny. No, more than a bit corny. Although with the way casting is going, I'm thinking it's going to be more along the lines of the initial
casting call assembly of the crew. Still corny, in my opinion.
5. In my opinion, Star Trek reached the pinnacle of its quality with the latter seasons of Deep Space Nine. Disagree with me if you will, but when the Next Generation started out, it was pretty much just OS plots under the guise of a new series. And we all know how that turned out. (Dirty bags of mostly water, anyone?)
Now, I am trying to be generous and give it the benefit of the doubt. But after Nemesis, I'm just not too hopeful.