I have both licenses. GMRS was my gateway drug into ham. Around my area, GMRS is very popular with the offroading crowd, which is what attracted me to it in the first place. But, GMRS is limited to 50 watts, and it has very defined frequency usage, making in not a lot of fun compared to amateur radio. There are a half dozen GMRS repeaters in my end of the state, but they are private and run by a club which requires membership.
It has already been mentioned that the CCRs are not legal for GMRS, but there are a slew of offroaders that are using them on the GMRS channels. I have also seen them used on GMRS by play warriors at the ranges.