I got a used version of this amp several years ago, and though I don't use it much (having switched to modelling since moving to the west cost), it's still working today despite going on a US tour, a cross country trip to California, and countless hours being tweaked and played and pushed to its limit.
The cleans are to die for; slight compression (maybe) and it doesn't matter if you're running a single coil, humbucker, p-90, et all. It's bright, it's beautiful, and i would usually run it through a chorus and delay through the FX loop (when it decided to work, but then again I also purchased it off of Daddy's Junky Music for like $200 and have no clue what kind of history it has before me).
The distortions are okay - pretty standard buzzsaw tones, good if you're going for metallica or mid-late era pantera (the latter especially - that mid-scooped tone is what it does best). I've heard better, but for a solid state amp, especially one as old as this (I'm not sure the exact age, but it was already very well loved when I got it, and it's been close to a decade since then). It also runs pedals very well, so you can use overdrives and distortion boxes to essentially add new channels. It's decent for low-mid gain stuff, but shines when the gain is pushed past 1 or 2 o'clock (higher than that though and I've found it gets a bit too noisy). I'd recommend getting a noisegate for it, but aside from that it's hella tight sounding, handling everything from low tunings (i've gone to a low A with no loss in quality) to high solos (again, great for 'tallica/'tera), and honestly its shimmering cleans work well with everything from metal and rock to jazz and pop (i let a friend borrow it for a ska show and he fell in love with it).
Since it's a solid state amp, and an early one at that, it lacks a bit in the warmth department, though it cuts through a mix like butter (so long as you don't eradicate what little mids it has). Also, for the love of whatever entity or non-entity you as an individual have put your faith in, I do NOT recommend mixing its gain channel with a pedal. It'll sound like ass. Trust me. Overdrive, distortion, fuzz, that gain channel's meant to be on its own, and sounds best as such. Even with the gain setting low on the amp, adding anything but a light boost will cause the signal to become a haven for harsh noise you didn't even know your guitar/amp was capable of producing.
It does have a penchant for overheating if you push it, though (a problem that's apparently relatively universal, as i've discovered through a cursory look through reviews in an attempt to discern how old the amp actually is) - this problem has apparently been solved in the G2 and G3 series, but the OG model can get hot and even burn out if pushed too hard. Not that you'd need to, of course - since it's solid state, it'll give you the virtually the same tone regardless of if the master's at 2 or 10, making it great for bedroom practice.
So yeah, final verdict: It's not bad. No 5150 or dual rec, but it'll get the job done, and since it was originally designed as an entry level model from what I've seen, it won't break the budget to pick one up used if you can find it. However, be mindful of it's level and temperature. I probably won't be bringing this on tour again (maybe as a back up, but definitely not as a main amp), but if you're low on a budget and just need something to kick some ass, this is your guy.