I'm old fashioned and for me, personally, you can't beat a good old fashioned work out in a class - the instructor really motivates you. I work that little bit harder in case anyone thinks I'm a lazy/unfit/fat bag.
That said, anything that is fun which gets your ass up of the couch and moving can only be a good thing.
Do you have a friend that has one that you can maybe try before you buy?
xx