I disagree with that assessment, as well. It's extremely easy to use, if you've worked in a physical recording studio, or if you've used Pro Tools (or any other traditional multitrack recording DAWs). You don't need to know the hotkeys, but if you do, you'll work faster. You don't need to customize it, but it's very customizable.
But, it isn't obscure. The GUI is clear and simple and well-documented. And, I didn't find the learning curve steep at all; it was almost instant. I mean, I literally don't remember a period of "learning to use REAPER", I only remember starting to use it, and having it Just Work. I went to school for audio recording, and have worked off and on professionally as an engineer, so I suppose that may have shortened the learning process. Which is why I say it's a tool for engineers who want to work with a traditional recording studio environment. REAPER is exactly that. If REAPER has a learning curve, it is merely the process of learning how to record in a multitrack studio workflow.
The REAPER user guide runs to 468 pages and barely scratches the surface. REAPER shines because it's massively customisable through ReaScript, JSFX and custom actions. A lot of essential functionality isn't developed by Cockos, but is part of external extensions - you'll need SWS installed for bread-and-butter stuff like r128 normalization, track notes and groove quantize.
REAPER is much more limited than Pro Tools or Nuendo out of the box, but it's vastly more powerful overall. You can use REAPER without learning it, but you'll miss out on most of what it has to offer.
That may speak more to what you're doing with it. I've never needed extensive customization or extensions to do what I needed to do in REAPER, and I've been using it for many years (maybe since the beginning...I bought it very early on, and while I kept alternatives around for a few years, it rapidly rose to the top).
But, again, I use other tools for my MIDI sequencing and composition tasks. The MIDI and sequencing and loop-based composition side of REAPER is weak. But, the multitrack recording capability is quite strong, IMHO, and very easy to use. Maybe with extensions and going deep on scripting and such you can make it work well for those other tasks, and perhaps that's where our communication is breaking down. For me, REAPER is a super reliable, super fast and efficient, multitrack recording DAW that works exactly the way I expect a multitrack to work. I rarely need docs, I rarely need to fumble around looking for what I want to do.
I did note, in the distant past, that REAPER wasn't really competitive with Pro Tools for broadcast and film production work. While it had SMPTE sync, it was missing some other stuff...that I can't remember now. I guess R128 fits into that category of film/broadcast stuff that REAPER doesn't do well. It's cool that there's a set of extensions that covers some of that. But, by the time you're doing advanced stuff like that, it's always gonna require scaling a learning curve, right? I mean, Pro Tools isn't easy to use for advanced stuff (or for any stuff, really...I find Pro Tools somewhat unintuitive, when I haven't used it in a few years and sit down to poke at it again).
But, the comparison to vim or emacs only seems apt once you're doing hard things with it. I stand by my assertion that for the simple stuff, REAPER is very easy to use.
Thanks for bringing SMS to my attention! Looks cool.
I agree with this assessment as well. REAPER totally has the power of vim or emacs, but when I started out and knew almost nothing about multitrack recording, I stuck with REAPER because its defaults were so easy and I didn't feel handicapped. The UI is so logically laid out and it really helped me understand routing and signal path in a way I didn't before, when I was trying to use other DAW's with less success.
But, it isn't obscure. The GUI is clear and simple and well-documented. And, I didn't find the learning curve steep at all; it was almost instant. I mean, I literally don't remember a period of "learning to use REAPER", I only remember starting to use it, and having it Just Work. I went to school for audio recording, and have worked off and on professionally as an engineer, so I suppose that may have shortened the learning process. Which is why I say it's a tool for engineers who want to work with a traditional recording studio environment. REAPER is exactly that. If REAPER has a learning curve, it is merely the process of learning how to record in a multitrack studio workflow.