I do NOT miss being a teenager. Whoever said that they are the best years of your life was completely misinformed. lol
When you're a teenager, everyone is so emotional and there is so much drama surrounding everything. Everyone is also trying to figure out who they are and what they want to do in life. Everything seems so complicated.
That being said, I do miss some of the things that I did as a teenager - band competitions, my first job (ok, so the people moreso than the job lol), and having fewer responsibilities.
Overall, there are some benefits to being a teen (i.e. fewer responsibilities), but they do NOT outweigh the benefits of being an adult.
Do try to enjoy your teenage years, though. While there are probably better times out there in your future, enjoy today - just be sensible about it. ;-)
I'm 29, pushing 30. :-)