I have one, along with a Burns Brian May guitar. Definitely could sound like the man himself if I could play like him. I just choose not to (practise).
The original Deacy I believe was a speaker and a battery, so no volume or gain. The VOX one has all the knobs you'd expect from a combo, but there are some really odd design decisions. One that for the life of me I cannot understand is that using the headphone output doesn't cut the speaker output, so you put some headphones on and your neighbours will still hear you.
Reliability wise, the thing has failed on me and been repaired. It's old, but I hardly play it so that's not a ringing endorsement. If you like near Oxford you're welcome to come try it. It's currently gathering dust under my desk at work.