I had one of those years ago. They feel pretty good, but not therapeutic like a real massage. I would definitely try before buy. Sometimes they just don't fit your anatomy.
On another note, I just had a deep tissue massage and I feel great, much looser and am standing taller. Now this massage was a massage in name only, it hurt like hell a lot of the time. I was close to tapping out a few times. Not some geisha girl lightly rubbing you down. Although that sounds good,too.