I have the Mustang MIT 70 automatic - not a super high end model, but it gets the job done. I Bought one a few years ago and really like it because I can wear it with a t-shirt or over top of a jacket or sweater with just a quick adjustment. Once its on, I totally forget about it.
I bought it because I actually wear it and wanted to set a good example for my son. I found I never wore the more cumbersome foam life jackets. Once I bought mine, my wife wanted one as well - and then I ended up getting one for my Father-in-law (who otherwise never wore a life jacket).
I always wear mine and the rule in our boat is that all kids wear life jackets. I've been out with other people where the kid kick up a fuss because the parent isn't wearing a life jacket. This makes it a non-issue, I'm wearing one - you are wearing one - end of story. If i have an adult guest on board, its their choice - but if they have a kid - the kid wears a PFD or they don't get on board.
PS - I also like that the Mustang life jackets are now certified for both Canada and US.