I always planted in the ground until this year. This year I got 5 earthboxes, then loved them so much i got 5 more. Still planted in the ground too, but i have to tell you, the plants in the earthboxes totally "ate their lunch". I think it is not an exaggeration to say they grew about twice as fast, less disease, and I have had the best season ever in terms of productivity.
They are still alive and I have never had tomatoes past the end of April before. (Our reverse growing season here has us start seeds in late August)
I am going to buy 15 more this year, mostly because I am OUT OF CONTROL now
I would say, just do it, you only buy them once in many years.