you have to like the Mesa sound. if you dig it, go for it. but realize that the differences between your guitars will be minimized. i love my Subway Rocket, but there's just no point in playing my tele or Ric through it. they just sound like noisier versions of my humbucker guitars. the differences are far easier to hear out of my Allen.
I have a single and I've played a shit load of other singles, duals, triples, 'verbs and trem-o-verbs..especially series I models..and you only really marginalize the difference between guitars when you are playing with some serious amounts of saturation, especially in modern mode. Playing in other modes, even vintage with the gain dialed back a smidge doesn't obscure the tone of the instrument.
Anyhow, It's basically a Single recto w/ reverb in a 1x12 combo package. 50W with a 6L6 power section. It should have two channels, each with two modes. Channel 1 has Clean and Pushed mode. Channel 2 has Vintage and Modern mode. Each mode alters the amount of gain available and the voicing. Channels are foot switchable, modes are only selectable on the front panel. IIRC the two channels have independent reverb controls and the other tone/vol controls are independant (overall master vol is shared). Effects loop w/ mix/level knob.
The thing that throws a lot of people with these amps is that the treble knob also alters the range of the bass and mid controls. It's not one of those set everything to 12 o'clock and rock out amps. You have to dial it in to your liking, being aware of how altering the treble changes the other controls. The gain control also goes to 11....and that's too much really. TBH, most people have a hard time dialing these amps in. The 1X12 combos are great for home/jam/club use but if you're really looking to get volume and play with plenty of aggression, you'll want an extension cab. I run my head into a 2X12 these days.
Tonally, I think the clean channel is plenty usable (and many people agree that the series I 50s are the best of the bunch on the clean tones) and overall the amps takes to pedals nicely. Pushed mode doesn't do much for me and I'd rather drive the clean mode w/ an OD. Vintage and Modern modes are that different voicings of that trademark cascading gain/Mesa tone; modern being the one most people are familiar with. Don't skimp on tubes with these amps either.
800 is good but the market is pretty soft and you might be able to get it down a little more.