Can't tell from your post if you 1) are looking at one wondering if you should buy it or 2) bought one and are disappointed with the results of using it on a project.
Either way, I would guess that most people who come across it blind echo the comments of honeydokreg--I know I thought it of an overpriced piece of MDF when I first saw it. I am purely an amateur trying to learn to build cabinets and furniture.
I don't have a traditional WW bench.
The MFT gets more use than any other Festool in my shop. Clamping is my #1 use--perhaps if I had a traditional bench I would use it instead, but maybe not.
Yesterday I need to cut a half-circle out, decided to use a router with a trammel base (std accessory with the 2 1/2HP Triton router). HAd never cut a circle with a router before, was a bit puzzled how to not cut through the workpiece into whatever it was sitting on. Long story short: wound up clamping the workpiece and a piece of sacrificial particle board sandwiched on top of the MFT. The ability to clamp THROUGH the table instead of just outside it is powerful, since you can position pieces in all sorts of weird ways. the combination of the clamping elements to hold things laterally and the "normal" clamps (I like the fast ones) to hold things down gives me a lot of flexibility in clamping: panel glueups, jig holddowns, alignment setups, etc.
Without a normal WW bench I find hand planing on the MFT troublesome. I could fix that by attaching the table to a studier base; perhaps I will. Plus the ability to clamp on the side of the table to hold something like in a traditional face vise isn't nearly as powerful as a WW bench.
I can't imagine using the Domino without the table--I did a (for me) tricky Domino joint yesterday and the results were perfect--required the clamping flexibility of the MFT.
I do all my sanding there. I have a little $20 stool from Ikea with a back, I hook up my Festool sander and vac, clamp my piece, turn on the radio, and go to town. Takes ALL the pain out of what used to be a nasty noisy job.
And the MFT + TS-55 is a hard combo to beat. I don't use that saw as much as others do on my MFT--it's primarily a sheet goods saw for me (cut downs on the floor on some pink foam). The table saw and SCMS do the bulk of ripping and cross-cutting. However, when I need to trim an edge off a panel or piece of plywood--especially when it's slightly angled to match another piece or to bring something square, I can't think of a better tool. Or, say you've got a bunch of little pieces that you want to the same exact length. You could set up a stop block and cut them repetitively on the TS or SCMS, but you can also lay them all down on the MFT side by side and make one cut. The guide rail provides enough pressure that nothing will move and the cut will be perfect.