"Absolutely an amazing value at the price point. This is mostly a first impression review as I've only had the amp a few days, but it *definitely* is a worthy replacement for the GX series that were beginning to fall behind the times. This amp represents a trend occurring in the last few years of modeling the preamp and output sections of tube amps separately - rather than attempting to having global amp models. The idea being to get those to behave in more "tubelike" fashion. Throw in the digital perk of being able to set those settings in easy to recall presets - and viola - an amp that has tweakable tubeish sounds and the (huge!) bonus of being able to store and recall several amp settings. For me, the reference on this idea was the Blackstar ID TVP amps. Sure, VOX (VTX) and others were also going down this path, but the Blackstar ID TVPs were purist in having a very tweakable output section modeled after several popular output tubes and a spectrum of preamp voices with adjustable gain. I have a Blackstar ID TVP 60 head - a 100% SS amp known for a very good tube sounds a large variety of preamp voices. It really does go quite far in matching up against all tube amps. The feel of the Katana is that it follows the same avenue and intended audience. I'm going to use the Blackstar ID TVP as the primary comparison. Both have an amazing tube sound and punch. Dynamics are there for both, a bit more for Katana. Both have preamp voices that are basically cleans - crunch - OD. The cleans for both are magnificent - slight edge for Katana - crystal clear yet warm. The crunch on the Katana really shines. To me - a weakness of the Blackstar. I've disabled the noise gate on it, but just doesn't have the dynamics and sustain of the Katana. The OD settings on both are very good. There are more options here for the Blackstar, and they are very good. Most metal types agree on this in general for Blackstars. Overall - in the preamp section the Katana is better. All of the voices are just great! Both have power attenuation for the output section. The Blackstar really shines here. The Katana just has 0.5, 50, 100 watt settings. The Blackstar has a knob sweep. That combined with a master volume (on both) that preserves the tone excellently. Great control of your output section. Additionally the Blackstar gives you output tube selections, and they all give subtle variations to meaningfully play with. It may sound like it's overwhelmingly in favor in the Blackstar here, but I don't feel the output section is as big of advantage as it may seem - as big a part of the overall sound adjustment. It's just that the Blackstar is *very* tweakable past what you can do on the Katana. The Katana really sounds excellent and again responds well to dynamics of your play. Compliments the preamp voices well. Both sound great in most aspects of tube amps expected. Where the Katana really stands out is the effects. Boss really came out with *the* idea that I think will make this a dominant seller. Configurable effects that can be swapped out and saved in the easy to recall presets that both amps have. If you like Boss effects, and I think they make among the best, you are getting a treat with this amp. You get quite a good approximation of them on this amp. I've not played with the software to swap about the plentfora of effects, but I can tell you that the plate and spring reverb are nice! Also the only chorus I've come to really like - it's here. Can't wait to play with the software. Blackstar only has it's builtin effects. They are workman worthy and also stored in their presets, but fall way short of what you get - and can get more of - on the Katana. Really like this novel feature. It does however, put more focus on a shortcoming of the Katana. Only 4 presets, vs 12 on the Blackstar (actually 128 with software and the footswitch). Still, I think this amp raises the bar on amps - serves notice to the other amp makers. What you are getting for the price makes it really hard to complain. And it sounds great. Even the little 5" speaker is not bad. Boss really did their homework!
Quick update 4/21/2016:
Still marveling at the value this is for the $$$. Reverses what used to be typical of solid state. A couple of good sounds/settings - the rest being junk. This is the total opposite - find it hard to find something that sounds bad. Does the best job of anything I've ever played at covering a lot of territory, and covering it *well*. I can't see how any typical needs guitarist would be disappointed in this amp. I will try to update this again after observing the software side of working with this amp. So far it has been pretty dismal with trying to establish an environment on a windows 10 pc and updating the firmware. Really cryptic and couldn't get it going. Boss/Roland needs to address this aspect of the Katana's usability..."

"Yes, it's loud (when used with an external cab or speaker), and no, it doesn't sound like a crappy digital/modeling amp. And although so-called "tone purists" will still say that tubes are forever top dog in the amp world (full disclosure: I have a tube amp and love it), tubes aren't always practical or reliable. And unless you run some sort of attenuator, you're never going to hear your tubes pushed at full volume anyway.

This head is extremely versatile, and I can get a huge range of sounds from, thanks to the Boss Tone Central software. I use this to drive a 16 ohm Peavey 2x12 cabinet, and it pushes a lot of air. The onboard effects are pretty cool, but I've had the best results from getting a good baseline tone with the head and augmenting it with actual effects pedals. I'm incredibly stingy with my gear purchases, and I don't regret getting this amp.

My only quarrel is that I'm getting a bit more noise with high gain sounds than I'd like. But there's an onboard NS-2 (noise suppressor) that can be activated with the software, and I have an old-school noise gate on my pedal board, so that helps. It's also possible that there are elements of the tone software that I haven't fully explored to help reduce noise since the patches I've downloaded from Boss and elsewhere have much less noise."

"when i was in high school i was one of those that got a large line6 spider ii 2x10 (not even the 2x12) amp when those went on clearance. so given that was the baseline i had in high school, and then like a 10 year gap where i didn't get to play at all, to hear this thing with its different models, even if you don't consider it modeling because it's not traditional digital modeling, these things have come a long way. And for $350 brand new, that's a steal.
I'm just a bedroom player so as far as I'm concerned, the tones are great for the money (putting aside for now the used market, which always throws a wrench in value calculations). I'd still kill for a real tube 5150III but I just play in my garage so this amp, with a 2x12" laney cub cab, is just perfect to whisk me away to guitar playing land for awhile. The little 5" speaker built into it is real nice if i just want a practice amp level of sound. I really like the "5150" lead amp on this thing, it's the one i use the most. I have yet to play with the sneaky amps or even the built in boss things, but I do have the foot controller so i'm looking forward to continuing to mess with the katana for awhile."