I have only taught myself and would love to get lessons someday. I learned with another friend at the same time and it's awesome to play him as we are the same level. You can be bad at tennis to enjoy it, as long as your opponent is too.
When you first learn to serve the ball in court as hard as you can, it is a powerful feeling. I can serve maybe 4 out of 10 aces (or ace-type serves).
If you want to know where you or your opponents stand, use this link.
http://www.matchmakertennis.com/public/ntrp.html