there are so many wrons with that movie, but two things come to mind.
1- if why would they make it cgi for this. It kills the whole the whole legacy of the cartoon
2- If they HAD to make it cgi why would they mix reality with cgi like in garfiled? That´s just wrong. If they were going for cgi they should have at least made it a full cgi movie like shrek or Up not this garbage. But hey, I guess it is cheaper to hire crappy actors than to make cgi ones.