My son's birthday was this weekend, and this (and Juno) was what he wanted to see. There was some really cool CGI with sabertooth tigers, mammoths, and some Jurassic Park looking huge killer ostriches. The scenery too, with the pyramids being built was decent. I really wasn't expecting Apocolypto (which I thought was fantastic), but at times this movie felt like it was trying to be Apocolypto. The acting wasn't great, and you'd have to get past the "hmmm...this ancient tribe from 12000 years ago is speaking.....English," but while thought it was overall pretty good, I'd be hard-pressed to recommend anyone else dropping $8+ on it.
Now, I saw this movie with five girls who thought it was great, so your mileage may vary....but I thought it was just so-so. The big problem I had was with the two main characters, both of which I didn't think were likeable.