It depends. Like Brady said, it can be good or bad. Take the Lord of the Rings movies, for example. Great use of CGI in there, those are fantastic movies. Without it, alot of the movie could not have been done. But that was because the CGI looked great. When CGI is used and it looks like crap, then it sucks.
For example, I saw Diary of the Dead the other night. I loved the whole thing, except for the end scene. I'm not going to go into detail, but there was a CGI zombie head as the last thing you see, it was the only CGI used in the movie, and it looked like crap. It was so pointless, they could have and should have just used a zombie head like they had been the entire movie.
GONNA SMASH YOUR BALLS IN A VICE!