my seven month old would LOVE something like that... she can stand, but only holding on to something and with a parent to steady her, and she gets very frustrated when I can't sit around all day with a hand behind her bum to make sure she doesn't crack her head on the floor.
If the kid was five, sure, but it's a pre-walking infant.
I would have loved to have had one of those when my daughter was six months plus. She was constantly active and a constant worry, already. Just think, had I been able to stick her in that and let her work off all that energy, why... I might have had a life, and everything.