There is a good deal of misinformation on the Matterhorn difficulty that we'd like to clear up. Somehow we got the impression that the Matterhorn would involve extensive 5th class climbing. The "vicious secret," as Kai Wiedman put it, is that the Matterhorn is almost all 3rd class! The peak should not be underestimated because it involves 4000' of climbing on summit day, all at high elevation, mostly on 3rd class or fixed ropes, and in an area subject to deadly storms which contribute to the mountain's 500 person death toll (about 30 a year). Ice axe and crampons are generally necessary because there is a short stretch of ice before the final fixed lines. However, a competent party under normal conditions will not need to cary any rock pro or ice screws.
The rock is described in some books as "less than perfect," which we mistakenly interpreted as "bad". In actuality, when you are on route, the rock is not as perfect as Yosemite granite, but is generally solid and enjoyable. When you are off route, the rock gets looser, which is a good indication you are off route!
The climb is rated UIAA grade III-. We had a poor mapping of UIAA to Yosemite Decimal System ratings which put this as 5.4 or so. III- actually means 4th class. There are a few 4th class moves around the Mosley Slab, but there are plenty of fixed anchors along the route which the mob of guides use. Most parties rope up at the base, but if you are comfortable on 3rd class, it is more efficient to climb unroped until the Mosely Slab, and possibly all the way. There is also at least 600 feet of fixed rope along the route. It's battered but nearly 2 inches in diameter. On the upper section of the mountain, hauling yourself up the fixed line lets you make good time by bypassing the moderate 5th class rock. It's not as elegant as climbing the rock, but since the primary danger of the route is weather which gets worse through the day, speed means safety. On the descent, we rapped a few times from fixed posts, but soon decided that it was faster to downclimb unroped.
Finally, a word about guides. The mountain swarms with guides pulling their client up the mountain on about 10 feet of rope for $600 or more. Europeans seem to believe a guide is a necessity, but Sierra mountaineers who know how to efficiently travel in a roped team will probably enjoy the climb more without the guides. The biggest advantage of the guide is that no route finding is involved, so you will climb very quickly and minimize weather risk. The drawback, aside from the fee, is that you will be rushed up the mountain as fast as you can move, you'll miss the experience of finding your own way, and you are doubtfully safer since a belay often means that the guide holds the rock with one hand while pulling in your rope with the other.
The Matterhorn is a dangerous mountain; two climbers fell off and died while we were in town. However, we went expecting greater difficulties than we found. Under good weather conditions, no fifth class leading is necessary and a reasonably experienced party will likely prefer the experience without a guide.