Matthes Crest involves a lot of hiking and a lot of scrambling, without much technical climbing. The key to having fun here is knowing when to rope up and when not to which, obviously, depends on your ability and comfort level. If you try to belay the whole thing, it will be a long day indeed. On the other hand, going solo, I've done the car to car in about six hours (fast walk, but very little running). Strong runners could take several hours off that time, but slower hikers would want to add several hours.
Starting from the Cathedral Peak trailhead, follow the throngs for a short ways until you see a well-worn trail off the right that takes you to Budd Lake and on to Matthes Crest. If it does not look like a trail, keep going. Much of this first part of the trail crosses open slabs and veers well to the right of the creek that drains Budd Lake. Don't cross the creek until you see the grassy slopes leading up to Budd Lake. Once at the lake, the rest is obvious. Contour around the lake to the right (Cathedral Peak side) and head for the obvious sandy slope leading up to the Echo Peaks saddle. Once there, follow the use trail down until you can easily cut across the slopes to the far end of Matthes Crest.
Once at the base in the saddle between the crest proper and the subsidiary outcrop beyond, you can head up anywhere. Most parties stick to the crack system, but the face is well-featured and easy to climb almost anywhere. Once at the top of the first buttress, just follow the ridge line, often going a bit to one side or the other (usually climber's left) until you get to the twin peaks in the middle with a saddle between. The easiest route to the saddle starts from the summit and head somewhat down and right. A little less exposed but not as nice is to come back a bit and drop down before traversing into the saddle.
Getting out of the saddle involves just a couple of moves of 5.6 to get you up the initial step and then it's all easy from there until you get pretty far down the ridge. Near the end there are some gendarmes that pose some challenges.
It is possible to bail to climber's left at almost any point on the route, so it's quite friendly in that respect and an excellent introduction to Sierra scrambling.
Reference: Moynier-Fiddler, p. 274