I have a Solidoodle 2. I've replaced the extruder with a printed one that's much better than the laser-cut acrylic that's included, but otherwise, it's been an excellent piece of hardware.

Lately I've started printing in "618 Nylon," a polymer which prints detail more easily than ABS, does not require bed heating (saves lots of time), and is much stronger than PLA.

I don't feel that 3D printing lets me do anything I couldn't before, but, as someone who makes things, it does let me take hardware from idea to conclusion much more quickly. So far I use it mostly to make parts for hobby projects, like the frame and landing gear for my quadcopter as well as enclosures and fastening hardware for an electric bike and control system.

I don't see FDM 3D printing disrupting traditional volume manufacturing in almost any industry simply because it's slow and finicky compared to subtractive CNC (milling) or molding. However, if you make things personally or professionally 3D printing turns any situation where you'd be Dremeling, drilling, and sanding a prototype to test before paying a shop to make samples for you into a pleasurable and cheap experience instead of a painful and expensive one.