I've only been to Relate by myself - it was helpful. I have heard stories of absolutely awful Relate counsellors, who imposed their inappropriate views on their clients and/or failed to understand abuse. By and large, however, feedback is overwhelmingly positive.
Relate impressed me most in what they did with a male colleague. We worked in a macho sales environment, where male infidelity was not just expected but celebrated. My friend Mick was a nice guy and all, but was very much a player. He started to change - became a more 'real' person, his conversation had more depth and he somehow seemed to be getting more intelligent! After a bit of probing, it turned out he & his wife were going to Relate. It was the making of him, I swear. They did stay together :)
Where the counselling fails, I often think it's because Relate is usually people's first expereince of counselling and they tend to place too much faith in the counsellor - who is, after all, just a human. If it 'feels' wrong (or maybe even as a matter of wise consumerism), I'd suggest seeing another counsellor independently for another perspective on the way your Relate sessions are unfolding. Or, of course, you can do that on Mumsnet 
This turned out longer than I intended - sorry.