Wonder Bars are good. As a transient apartment dweller I hauled around a Wonder Bars, it was 16" or 18" long and its blue paint and label became something of a reassurance. Over the transient years it got used a lot and never let me down.
The Wonder-Bar isn't really special. Plenty other similar units out there. Stanley makes a nice line of spring-steel flat bars. From 6" to 24" as I understand it. 16" to 21" seem handiest for urban search and rescue or escaping a structure.
Flat bars are possibly the most adaptable and widely useful of designs. Wedged under a door you can step on the other end to raise the door into place while keeping your hands free to get the hinge ins in. The wide bar won't roll out of position like a round bar will. This makes them superior for use one-handed when you use foot pressure to lever something into position.
Wedged between concrete blocks or wedged against a wall a flat bar can be used as a temporary step. Much harder to do that with a conventional pry bar.
The flat surface and easily filed or ground spring steel makes them functional scrapers for removing linoleum, ceramic tiles, spilled concrete, or ice.
Very handy and quite cheap. What's not to like.
On the other hand I agree with
I found the Fubars to be very unbalanced when I played with them at the store. Just my 2c; I thought I would like them but the business end seems overly heavy and I imagined getting very tired when using them.
I tried the Fubar and found that it is a crude, poorly balanced, club. The pry end bends the wrong way if you use it right handed. Holding the grip the the sharp pry wedge hits my wrist. The weight is centered half way down the handle so it compromises the hammer function. For less money you could buy a good flat bar and a three pound engineers hammer that would work better as either hammer or pry bar and they could be used in concert. A trick the Fubar can't do.