I think it would be terrible, you'd have to keep it secret lest you end up locked in a medical facility being tested. If you were going back to being 6 or even 13 you'd probably end up alienating yourself because your peers would be so insufferable, not to mention school would be tedious as hell.
If you've moved out then reverting back to a time when you were dependent on your parents would be a nightmare. You'd have so little independence in comparison, no money (and jobs pay a pittance at that age), you can't drive, you can't go out and you can't crash at a friends house one night because they don't have their own place and they're an annoying little runt anyway.
Not to mention, people would be so uncomfortable around you because you know so much more than you should. Can you imagine how it would be if you met a long-term partner and it was their 'first' time meeting you? Or if you let slip something about 9/11 a couple of years before it happened, and by the way,
let's not get any asinine notions that you could somehow prevent that tragedy or Michael Jackson's death. Also unless you have an astonishing memory, or some sort of preparation before going back, you're not going to be predicting lottery numbers any time soon.
I'm sure there are plenty of other reasons why this fantasy would be pretty shitty.