Hi Raj,
Most of the guys starting career in SAP that would be in SAP support only. Even I started my career in SAP support only. As a starting period we have take this support opportunity somewhere if we want to crack into SAP. However, 4 years is longer period but if you look at it in other way, nowadays 4 years nothing... as time is flying like anything. You can go to implementation after 4 years and you will also have good experience at the time.
Just check this forum how many of guys wanted to get into SAP, so if you see that then you don't regret this opportunity.
Something better than nothing.
Regards
RC Gopi