Not that great if imo your comparing them to the more serious Resident evil games themselves.
I'm a huge zombie fan, love the Romero films, Fulci films, love the homage film Shaun of the Dead, Return of the living dead franchise & many others.
Don't get me wrong at first when RE 1 & 2 came out I had high hopes of them being good when Romero was tapped to direct, when he got the boot I tried to keep an open mind and see the film. To my dislike, they weren't completely unwatchable but when they were given the source material (video games) and screwed that up I knew that the series had no chance to redeem themselves.
Resident Evil Extinction wasn't bad, at least compared to the first two films (& btw it borrowed from Romero's films I noticed) it did away with the techno music and took a semi-seriousness to it but the first 2 films damaged the series imo and couldn't shake away what they had done.
Maybe they will re-do the series as a whole (as hollywood likes to do many times with other films) & hopefully they will follow the games story more closely and do away with trying to please certain audience demographics.