I have bought and used a number of controller keyboards and sequencers, and still have venerable objects such as the Yamaha QX-5. None of them have quite hit the bullseye in terms of features, usability, or in some cases, reliability. I've had poor experiences in general with Arturia gear, a Minibrute with dead keys, and a small controller keyboard that simply would not reliably connect over USB while a Samson keybaord managed this just fine. So I felt a lot of caution when I finally opted to buy the Keystep Pro (KSP).
I was keen to have a controller keyboard with sequencer(s) built into it simply because I felt that with everything in one place it might be simpler simply to start up the keyboard and get a new idea down in the shortest possible time.
The KSP is a very capable keyboard and there are a number of video introductions and tutorials online that will help you get to grips with it. The good news for me was that it seems to be reliable for the uses I put it to. I've not tried connecting it to a computer as yet. That pleasure is yet to come!
I especially like the fact that you can build entire tunes around the pattern>chain>scene system, with patterns chained and then sequenced on a larger scale within a scene, allowing me to build tunes around a verse and chorus pattern and then sequence those verses and choruses at a higher level. The ability to assign midi in a fairly intuitive way is also helpful, although I would welcome a change that allowed me to reassign a midi channel "on the fly" and then overdub parts for a second instrument somewhere along the same MIDI chain. There are two MIDI outs on the rear panel, which is better than just one, but with a lot of MIDI outboard equipment there comes the need to send multiple channels out along the same cable, and the ability to stack MIDI channels through various outputs would be great for usage cases such as mine.
Generally, its very pleasing and I can already see how it will help my productivity. It's well built, although the keys are smaller than is ideal for my fingers. it'd hard to play something quickly with enough accuracy, at least in my case. I'm used to full-size keys since I have full-size fingers!
I would prefer the manual to have at least a section where it is task-orientated rather than running through the features. A section on starting a track, overdubbing and editing, etc. Again, there are video tutorials online that will help with this. The better ones come not from Arturia but from popular Youtubers such as Loopop.
I've recently run into some limitations, however, since this and indeed most Arturia equipment seems focussed on live performances of club grooves that a player can then improvise with. For example, I recently had a long melodic line that runs across 32 bars at a fairly slow tempo (66bpm) and sat down at the keyboard thinking that I would simply be able to set up the metronome and then play the phrase in to a new project. But I couldn't, because the maximum bar count in the Keystep Pro would not be long enough for the whole phrase to be played in at the desired tempo. Additionally there were two pickup notes before the "one" of Bar 1 that needed to be played, extending the bar count by one. I hoped the KSP would do the job and had to resort to a DAW instead. In my setup this isn't best option for jotting down a very fast musical idea, and I would have been better off simply playing the audio into a portable digital recorder!
The v2 firmware has improved the KSP a great deal but there is hopefully room at some point for a freestyle record option where a musician could perhaps tap the TAP TEMPO button 4 times, the KSP then counts 1 or 2 bars of count-in where the KSP is listening for notes before the "one", and then begins recording in an unbroken stream until the player hits STOP. If this had to fit in with the KSP's pattern/chain methodology then perhaps the KSP could record patterns and simply auto-chain patterns until some far larger limit was reached. There's enough contemporary music made around short loops/sequences as it is, without the tech forcing people to have to think in that way! So, for the moment, I will use the QX-5 as my notepad after all.
The QX-5 has another virtue, the ability to emit patch/program change data which, if it can be done by the KSP, certainly isn't obvious! As it is, the QX-5 needs to be slaved to the KSP and send patch changes to any synths that can accept them. Fortunately for me, all the synths on the second MIDI output are analogue monosynths with no capability to store patches, so I need just one channel to carry patch changes. Or use the DAW, which I hoped the KSP would free me from.
So, it's not quite the answer to everything that some people might think it is.
It's hard to complain about such a device as the KSP, but the QX-5 was around in 1986 and offers sequencing features that should be commonplace by now. Perhaps I'm missing the point, thinking of the KSP as a controller keyboard when it's simply a performance device, but it can be frustrating to use a device that doesn't quite cover all of our workflows. Even more frustrating to make it the centre of a small electronic setup only to find that we need to add back some old equipment we thought we'd replaced.