Having played Somerset yesterday in a foursome with Dan Kelly, I have to echo what has been said here by John Conley and Wayne Freeman: Somerset is a wonderful golf course, in my opinion superior to Interlachen, and one that continues to grow on me each time I'm lucky enough to play it.
Though it is surrounded by residential roads, there is still some room to add a bit of length, but the current back tees -- discreetly positioned, as John said, in a way that does not remotely alter the essential nature of the parkland-style course -- provide a very strong test on many of the par 4s, some of which are in the 450-460 range. If it's 480-yard par 4s you need to test your game, however, look elsewhere. Somerset isn't that kind of course.
The original topographical map from 1919, with the original tees and greens superimposed, hangs in the men's locker room. On a nearby wall is a map of the re-routing from 1950, undertaken by Stanley Thompson. I have no idea how much of the orginal Raynor remains, but several of the greens are reminiscent of Thompson's work at North Oaks, while a couple of others -- notably the par-5 16th -- seems more like a Ross.
Raynor's touch certainly seems to still be in evidence; number four features a wonderful Redan-style green, and number 12 has a slight Biarritz trough through the center of the green.
Fortunately, new members -- what few there may be -- are advised to appreciate the clubhouse and the course the way they are, because the older members have no intention of changing them. Hallelujah.