We have been members of Netflix for about six months now and enjoy it. We do not have the instant viewing, however. You do need to have a fairly fast internet connection for that and ours isn't yet.
We get the two movies at a time deal which is about $14 or so. Once we mail back a movie, we get one back in about 2-3 days. The only drawback we have had is getting a movie and having it skip or get stuck and having to send it back to get a replacement.
When that happened, I called immediately and told them about it and they sent out a replacement immediately along with the next video in our queue, they did not wait to receive the damaged disc back first. They mail the replacement immediately. It was excellent customer service and very accommodating.
I don't regret it.