I've been eyeballing this aptly named tool for a while. My new house has a few extra walls, so I finally had an excuse to buy one. There are actually two versions of the 'Functional Utility Bar' made by Stanley. The normal FUBAR is a bit lighter, smaller and the prying end isn't divided. For an extra $10, I opted for the FUBAR Xtreme. It's a bit heavier than a medium size sledge hammer.
In the last few days, I used the FUBAR to punch through drywall, pry apart 2x4s and 2x6s, and literally shred a few of them along the way. It's fantastic for punching holes to see if wiring is present before you start using power tools.
Alone, the FUBAR is pretty handy. Combine it with a reciprocating saw (aka Sawzall), a pry-bar and a hammer, and you'll be ready to demolish just about anything in your way. If you've got much of prying to do, I'd suggest a normal pry-bar. The weight of the FUBAR can be a bit much for extended prying jobs - like pulling up carpet tack strips.
Is the FUBAR worth $40 and change? Yup. The combination of high mass and small profile make it highly effective as it delivers your wrath upon unsuspecting drywall and lumber. Just make sure you grab some padded gloves before you get rolling. (I use a pair of inexpensive leather workout gloves)