I have a Marshall AVT150X and it is my favorite. I have tried a few amp at the music store the day I bought this amp, in my opinion it had the best metal sound (was on sale at 900$ CD). It also have a great sounding clean and accoustic simulation channel. The first overdrive channel is good for those who like more classic rock style.
Personnaly, I choose the second overdrive channel, put the gain and volume at max, adjust the master volume, push the scoop button and get ready for some headbanging :)

There are also effects to choose from on the amp like Halls decay, room decay, plates decay, gated reverb, chorus, flange, delay, chorus room, ch/dly room and modulation.

Bottom line it is a great amp for the metal heads out there great sound,
2 downside : don't use the emulated line output, it sucks, mic it if you want to record and it is only one effect at a time.

Never regretted that purcahse.