The Jam series of amps do what so few amps can do effectively: They give you rock-solid, balanced and uncolored tone. I'll admit that this kind of tone isn't cheap, but with 80 watts of headroom in a (mostly) portable amp, I believe it's worth every penny. My only knock against the Jams is their weight—the 150 watt version is nearly 30 lbs—but the Jam 100 listed here is a bit more manageable at 24 lbs. I think for most players, that's a small price to pay for unbeatable tone, especially given the attractive $599 price tag of this amp.
I'm sure enjoying my Jam 100. It is by far the most clear and articulate amp I've ever owned. Plenty of headroom and no distortion at higher volumes. I've used it with my UST, Taylor ES 1.3 and Baggs M80 equipped guitars, all sound great.