I use this amp for extreme metal - black metal, thrash, and doom. I've used this for a few months now, playing a lot of gigs, and have lent the amp out to quite a few friends. It has taken all these tasks on and performed admirably.
The build quality of the amp is great. It's a nice solid body, all the input jacks are nice solid metal, and the switches don't rattle around or get loose. One minor complaint is that the knobs don't feel massively solid, but keeping the amp in a flight case negates this problem. I've never actually used the handles (due to the aforementioned flightcase), but they are solid enough that I would completely trust them.
The sound of the amp is great. There isn't a separate gain control, so the sound is very clean, but I happen to like this. It takes pedals with ease as well, so distortion isn't a problem if needed. The outputs are really easy to use, the manual explains everything one needs to know clearly and simply. Running at 8 ohms through a 4x10, the amp sounds great. Running the full 500 watts through a 4 ohm Ampeg 8x10 is amazing.
The amp is plenty loud enough for just about any situation. Despite being 500 watts and solid state, I've found that it is loud enough to match, and even overpower full band setups - certainly, in my power trios, I am constantly having to turn it down - I've never taken it beyond 7 at a gig. In full bands that I've lent the amp to, it's perfectly capable of matching two 100 watt tube guitar heads.
Overall, this amp is an absolute steal for the money. If mine gets broken or stolen, I would not hesitate to get another one straight away.
I was looking for a cheapish backup amp, with enough power to do larger venues without PA support, and the LH500 more than fits the bill. Simple EQ (bass/mid/treble) gets a pleasing tone very quickly. This amp is clean - you won't get any valve "grind" from it - but if you're looking for a lovely clean, warm, fat sound then the 12AX7 tube preamp certainly delivers. Matched with a 500W output stage, this is one very loud beast. This isn't a lightweight, but the build quality seems very good. Given it's price, this must be one of the best bass head bargains out there at the moment.