To what are you referring? Here are 2 possibilities:
1. The Port of the game from 1 system (PC or Console) to the other isn't great. Games start out on a certain platform and then have to be converted to other systems. Sometimes this conversion doesn't go very well. Graphics aren't as good, controls don't work as well, etc.
2. The ability to play the game online uses some bad ports on the network and people have difficulty without using port forwarding on their routers.