Are those oscillating tools any good?
My dad has a Multimaster and it's truly awesome.

Like any tool, there are jobs it is good for.

There are quite a few tasks I've found where it would have been really useful - mainly in repairs and renovations, where you aren't ripping out whole floor boards or walls or anything.  Those are things where a reciprocating saw, jig saw, circular saw or even a dremel tool (a cutting wheel is always the wrong angle.) won't work well.

He used it to cut out windows of my daughter's playhouse after we put up the plywood walls, and it doesn't do a great job on long cuts like that - he was cutting blind from the inside along the studs and the cuts aren't perpendicular to the sheet (but it's covered with trim).