I use Talkatone - an ad supported Google Voice app, and I wanted to try out Groove IP the other day. So I bought the pro version, but my experience was pretty bad with it. I tried making and receiving calls on it, and while whatever I say on Groove IP is heard on the other end almost instantly, whatever is said on the other end takes a couple of seconds before I hear it, which is terrible for carrying on a conversation. The situation is marginally better over wifi than over mobile data connections, but not by much. Thankfully, I got to do all these tests within 15 minutes of my purchase, and I hit the refund button to get my money back.
What's everyone else's experience with the connection?