Jillian Michaels Fitness Ultimatum has recently been released in the US. It is currently unavailable here in the UK so I've been unable to review it myself.

However the reviews on Amazon US do not bode well.

It looks like the control system is poorly designed, and the game itself, while having some advantages over Wii Fit (proper routines), is lacking the charm, detail and polish of the original. It looks like they forgot the golden rule of Wii games, the control system is everything, and the devil is in the detail of how you actually play the game. Many reviewers are reporting that is it unstable and glitchy, crashing consoles and locking up frequently. It sounds like this was a half-baked attempt to rush something out in time for the holiday season.

When it is available here in the UK I will do a detailed review and let you know how it stands up to Wii Fit.