Pros - Small, lightweight, all-tube, no BS, looks like Darth Vader designed a tube head.
Cons - Can't play stadiums with it.
Surprisingly loud through a PF-115HE, and can flip into the cab for transport too. Depending on your cab, maybe 50W isn't loud enough for you to be heard in the back of the club, but they probably have a PA, so run a single XLR from the post-OT direct out and straight to the FOH, and it will sound like the voice of God. If you play metal in a band with three guitarists and four drummers then you aren't looking at this anyway. Otherwise, this rig is unstoppable - all-tube, no fakery, makes your bass sound like a warm, breathing, living thing. Loves pedals and enjoys being pushed a bit. Looks cool. Has the same gain and EQ structure as a V4B. What's not to like? It's made in China, but then so is your iPhone, and everything else these days.
Pros - Sounds wonderful! Very versatile, and can be used without a cab connected.
Cons - Not easy to carry around if not in the flip-top configuration.
I became interested in this amp because I was nostalgic for the B-15N I bought back in 1969. The only reason we parted company long ago, was because I was flying all the time and the little solid state Polytone Mini-Brutes did such a great job for what I was doing.
This amp is quite versatile, and the front end of this thing is amazing. It allows you to dial in a wide variety of tonal colors, and of course there's that rich tubey goodness. I was quite impressed that with my upright and NS Design EUB I didn't need a preamp. Usually, for upright, I go right through the effects loop with a Zoom A1. I found the Gage Realist and the NS EUB sounded even better right into the PF-50T input than with a special piezo preamp.
In the studio, the direct outs are fantastic. No need for a direct box. I love the way it records. The tube cage gets warm, but certainly not dangerously hot or anything. I love not having a fan in the amp.
The only negative I could mention is that it would have been nice if they had put the transformers in identical cans and made the tube cage flat on top, with everything the same height, so if you have to set it down with the cabinet lid attached, everything's level. It would also probably be better in terms of it's aesthetics.
Overall, after giving it a workout in a number of different setting, I feel it's just a great piece of Ampeg gear, and I'd certainly recommend it, especially in the studio, and teamed with a PF-115HE or PF-210HE as a combo.