I play 3 guitars so when I got the head I ran it through the line up. A Squier Strat, Squier Tele Custom H+H, and modified tele with P-90 in the bridge position. I bought it for some gritty nasty blues tones. I like to crank it up and do penatonic scales for fun. I'm not a good blues player by any means, so I do it just to amuse myself and annoy my neighbors and wife. This amp is perfect for that. Will it satisfy your Tweed or Skylark "Jones" or GAS, probably not. But if you want an inexpensive tube amp that does what a small tube amp will do it's a good buy. You really can't find anything this good in this price range new.
The newer heads are quiet. Even with the volume pegged it was very quiet, even by solidstate standards. Pretty impressive, considering how noisey the first ones were reported to be.
Nice break up with the volume around 12 to 1 o'clock. With the volume cranked you get some of that spongey quality. With my single coils it's a little nassily, but I like that. Sounded pretty sweet on low volumes clean. Yea, it's only one knob you may be thinking, but it responds to your playing dynamics and guitar controls, so it's not really a limiting factor. I've heard an E-Q pedal can really bring out some magic in these heads. I'm not a tone freak so I wouldn't bother.
There's a lot of talk about modding these to get better sounds. Also, there's no limit to what you could spend on a speaker to find that ideal tone. I plugged in my 2-12's from a very old Peavey Classic and they sounded fine.
5 Year Warranty. Looks sturdy for a tube amp. Definatley well made. I don't think I would gig with it, it's really not that kind of amp, but if I did I would bring an extra set of tubes and not really worry about it.
I've been playing for 16 years or so. I've owned a few vintage 50 watt Fender Heads (64 Bandmaster and a 70's Bassman), A silverface Champ and Princeton. Recently I had Blues Jr (early Made in USA) and I think the Valve Jr while not as rich sounding as my vintage gear, definatley is a contender against the Blues Jr, especially since Blues Jr's have a so so speaker.