They're the same as the JTM series that I used to own, except they're black not the beige colour of the JTMs. As far as I'm aware, the electrics are the same as the JTMs? I don't think they changed them at all.
If you're using it at home and want a genuine tube sound at decent volume levels they're great. If you ever want to crank it, buy something else. My JTM was useless when it was fully cooking - the tone went mushy and it wasn't happy at all. Not what you expect from a Marshall tube amp.