I've owned two sets of these tires (three if you include its sister tire, the Michelin WeatherWise II, from Sears).
First set was on my old '97 Cadillac SLS, P225/60R16 97S. Previous tires were a set of Michelin Pilot XGT H4. The X Radials had about 80% of the performance of the Pilots, with a much better ride, and a much better tread life. I really felt that those tires out-handled their speed rating (which I've since learned isn't always that descriptive of a tire's performance anyway). When Consumer Reports tested this tire back in 2005, it got high marks for handling as well, so that seems to be a trend.
I was so impressed with them on that car that we mounted them on our '07 Town & Country with just 9,000 miles on the van (215/65R16 98T). The OE Bridgestone Turanza EL42 tires just plain sucked in the wet. They gave a very nice ride, but just didn't cut it on wet pavement. The Michelins stick much better on wet pavement. Though I haven't had any trouble with them in snow (even on 6" of fresh snow on an unplowed street), I have heard that their snow traction isn't what it could be. My van (and the Cadillac) has traction control, so you just set the throttle and let the van work it out, so driving withOUT traction control may be different.
I now have Yokohama Avid TRZs on my Corolla, with about 10,000 miles on them and I can't wait to mount a set of the Michelin X Radials to it. I really liked the Avids when they were new, but in the cold, the rubber compound seems rock hard, and they really stiffen up.