In my teens I had metal dental braces to correct both an overbite and some upper row gaps at mid line. I was given a retainer back then, but stopped wearing it many years ago. Over the year my teeth returned back to their original post braces position. I did not want to wear metal braces again for many reasons and opted for invisalign when my trusted dentist began to offer the procedure in his office. I currently on my 6th set of 13 (26 weeks) and noticing positive progression. My experience has been good so far.
The retainers come with added dental maintenance and must be removed for eating and drinking (except water). I would not recommend these for a teenager or a forgetful type of a person. The retainer could easily be thrown out (experience as a teen). Also if cleaning is not maintained I could see gum and teeth issues becoming apparent.
I'm liking the results but it comes with some discomfort with first few days of new retainer set and added brushing. I use a spray bottle with 3% peroxide that I use to clean the retainers and leave solution on when not in use (eating) and brush/rince them prior to reinsertion. Best of luck to everyone else