Jelly... I've never tried it, to be honest. I remember getting a ride to a presentation with a classmate of mine, once. She had a foot-shaped air freshener made of a gooey translucent material hanging from her rear view mirror... It was pretty awful smelling. That is my only impression of jelly.
I would never insert it in myself because of the harmful chemicals involved, and using condoms each time isn't exactly environmentally friendly (and nor is the jelly material for that matter). That, coupled with its inability to be sterilized, makes it a resounding "NO" in my books.
I'm particularly sensitive to chemicals on my skin and in the air, so I don't think I'd like to try jelly at any point in time. To each their own, though. The texture and the price must be its redeeming qualities... Maybe?