I don't know much about prehistoric times, but something about the dramatic story of D'Leh (the insecure caveman) and proto-Lohan seems historically fishy. 10,000 BC was a long time ago, and I can only imagine that specific details of that era are sketchy at best. Likely, this film is just another excuse for director Roland Emmerich (Stargate, Independence Day, and--let's not forget--Godzilla) to work some more of his CGI magic. While 10,000 BC boasts neither a compelling plot nor quality acting, it showcases enough photo-realistic mammoths, saber-tooth tigers, and killer ostriches to keep its audience entertained for 109 minutes. And believe me, folks: You have not lived until you've seen a killer ostrich tear through a band of marauding horsemen.
Of course, audiences do not go to a movie like 10,000 BC for its compelling plot and quality acting. They go for its action, adventure, special effects, and leather-clad cast of models-turned-actors. In this respect, 10,000 BC delivers up to a point. I would have liked to have seen more saber-tooth tigers in action, for example. I also kept hoping--just for laughs, of course--that the Lindsey Lohan look-alike would check herself into prehistoric rehab.
Ultimately, 10,000 BC is is neither the worst movie ever made, nor the best. If you have a spare 109 minutes (as well as a desire to see killer ostriches in action), you might as well check it out. It isn't a complete waste of time--in the way that, say, Titanic is--but it occasionally comes really close.
One more thing! 10,000 BC has a "twist" ending that sets a new standard for cowardly filmmaking. If I were a betting man--which I'm not, by the way--I'd be willing to bet at least five bucks that the ending was re-written by a test-audience.