You can expect a wide range of answers on this board. The suggestion of looking at festoolownersgroup dot com is a good one - a little less venom over there...
Personally, I have several Festool tools and an MFT. I have a good range of stationary tools as well (unisaw, dj20 jointer, drill press, band saw, miter saw, etc). For me, the festools take up about 10 percent of the space and do 90 per cent of the work.
I sold my non-Festool routers and sanders, just never used them after the green got its nose in the tent. The tablesaw doesn't get much use anymore, mainly for a large number of repetitive cuts or to use a couple of jigs I haven't converted to Festool yet. The other time I use the TS is when I have a setup on the MFT that I don't want to break down yet. Oh, and the TS makes a nice assembly surface.
As Chris said, the pieces work together beautifully. There is one power cord that plugs into your saw, sander, router, domino, etc. No clutter. With the rail and the mft, I make just as precise cuts as I could on the TS. And with the dust collection, theres almost no cleanup at the end of the day, and you are not blowing black snot out of your nose - those two things are worth the price for me.
I do still use the miter saw, though probably more for rough cuts than anything else.
One thing the MFT is not, however, is a hand-tool workbench. Just not rigid enough. Its fine for power tool use and assembly, but not for heavy duty handplaning.
It depends a lot of what kind of work you want to do, but maybe one could generalize that if space is a premium, dust control is important, and you aren't doing a hundred reps of the same cut, Festool could be for you.