I'll be blunt. Force Field as it stands today is not a good power set. However, that said, it's also underrated. Many people severely underestimate the benefits of both the AoE mez protection it provides and the endurance drain resistance it provides. Those are both valuable things, and still fairly unique. Believe it or not, Force Field is actually good on the hard mode ITF thanks to all of its +defense, especially if it's PBU boosted. It's just in the general level 35 - 50 content outside of some iTrials and the hard modes, it's really lacking.
Water Blast/Force Field Corruptor is a good combination. I advise you to stick with it and realize that even though many people aren't realizing it, you do provide a couple of benefits to a team.