I got my first and only betta (he's purple and his name is Ivan the Terrible) about a year ago when I got one of those plastic betta bowls with the hinged lid as a gift. Ivan never did much in there, and didn't eat much either.
About six months ago, I decided to put him in a ten gallon planted tank I have, where he has been living with four small congo tetras and a very small bushyhose pleco.
I certainly don't regret it. He's the happiest fish I have out of all my tanks. He will take a flake right out of my fingers, swims around all the time and looks like he'll go on forever. He even "trims" his own fins, which I thought was pretty weird until I saw another posting mentioning that this isn't abnormal behavior.
If anyone out there is considering liberating their betta from small surroundings, I would encourage it.