Ive been using GrooveIP for a couple of days and I find it more than adequate. I was on a 20 minute call (via GrooveIP) with Verizon last night, cancelling all my lines/plans and it worked like a charm. It's not quite as good as a solid cell connection, but probably as good as when your floating between 1 and 2 bars...sometimes a small amount of static or a slight lag in voice transmission, but overall, very good. I've only used it while on wifi and have read that it can be more finicky over your phones data connection. It seems to be all about your ping rate, with under 200 being needed, and under 100 being preferred. You need to play with the settings (speaker, mic and echo) while talking to someone to get it tuned in. The first time I used it with all the default settings, it sounded like an old fashioned long distance call (pretty bad). The truth is, in my humble opinion, cell phone conversations are mostly sub par at best. I've always noticed a slight lag in conversations, so this is really no different. Bottom line for me is that it works and it's a great way to put a serious dent in your cell phone bill.