Personally, I don't like 'em. I listened to the new "Punk Goes '90s: Volume 2" that came out, and it is just plain awful. Especially Falling In Reverse's cover of "Gangsta's Paradise", which was nearly unlistenable and a disgrace to the original.
The only ones that I enjoyed were the "Punk Goes Metal" and the "Punk Goes '80s" ones. They actually got bands that I liked for them, like Relient K, RX Bandits, The Aquabats, and Sugarcult. Also, "Punk Goes Metal" was actually punk rock.