Surprisingly good for a modeling amp. Manual over-sells the power attenuation feature; while it's useful, you *CAN'T* necessarily get good sounds at a lower volume with it. All the distortion sounds are awful at low volume settings.
I'm using this with a G&L Tribute ASAT Special. Nu-metal is useless but the other models seem decent. No real "crunch" but that's expected and probably dictates how accurate the modeling is; the beefy G&L single-coils sound like beefy G&L single coils. I can't wait to hook a humbucker-equipped guitar up to this and see how it differs.
Favorite model? AC-30 TB with the gain up. Rolling down the volume on the guitar lends a nice clean sound that's still lively, while raising it a bit distorts things enough for extra sustain but still retains character; things don't "fuzz out". This is my anti-heavy distorted rock sound: somewhere between Tom Herman on the first couple Pere Ubu albums and Steve Albini's work on Shellac, though not as trebly as the former or as crunchy as the latter. The key thing for me is that I can still hear all the nuances of the pick attack and not have a ton of noise or hum in the background.
Effects-wise...eh, guess they're okay. The delay is nice, though the time could be longer. The others are kinda okay but don't vary in range enough from subtle to extreme and are thus useless to me. The exception is probably the compressor; amps should probably have compressors built-in anyway for clean playing. But the effects are ultimately only so much use without the extra-$25 footswitch that should've been included. I'll buy it soon but it's pretty idiotic not to include it with an amp that's got so many settings packed in from the start.
Again, plastic jacks worry me, as do all of the reports of this thing having broken down and the bad customer service. Self-service doesn't seem like much of an option, and with the short warranty, it concerns me. I'm not adverse to opening it up myself, but a real-live service manual would be nice.
OTOH, chassis seems pretty solid for what it is. That ugly metal grill will make sure nothing ever punctures the speaker. All the screws seem tight. For a sub-$1000 amp, I guess that's about as much as a guy can expect.
Bottom-line: I bought this to play at home and occasionally drag to a friend's place. If I'm going to gig out, I'll buy something more solid.
Does what it's supposed to. I expect to get 3-5 years out of this amp as a home practice/recording rig and that's pretty much it. The sounds it yields are pretty versatile and most are decent. It's cheap compared to other amps that yield the same quality of sound. It sounds significantly better than other modeling amps in the same price range. It's the right size for playing in my apartment and in friends' basements/garages/etc. Couldn't ask for much for at under $400.