If you are into playing with the various NI instruments, having a NI keyboard and using their komplete kontrol software, it’s far far more user friendly than having another make midi controller etc.
If you aren’t really interested in NI instruments, personally I don’t think it’s worth buying.
I am heavily into synths as well as pianos, I have komplete 12 and their 61 note mk1 synth style keybed and I love it. I’ve had NI synths for years, I only got the S61 this year, and it makes browsing/editing their software so much easier and user friendly, I would never get rid of it.
I also own Arturia V6 synth collection, and those also have NKS (NI keyboard kontrol software, allowing NI keyboards to edit and browse the synths/patches etc) compatibility, hence I can browse their sounds and NI sounds all at the same time from the NI keyboard.
The Mk2 has extra features, but none are must haves for me (got mk1 cheap second hand) plus the mk2 series currently lacks MCU support, meaning the transport (play stop ) buttons will only work with DAWs specifically programmed to work with the mk2, whereas on the mk1, as it has MCU support, the buttons can be made to work with any DAW.
I wish I could find a cheap 88 note synth style non weighted keyboard to go alongside my 61 note, so I have access to the full note range, but for synth playing, I don’t want weighted. In the end I bought a cheap M Audio keystation 88, it’s sort of weighted, but is about as unweighted as I can find (and very poorly made, when I find a better full length keyboard, this will go)
Had I decided to keep playing the piano there too, I would have kept my Kawai MP7, but decided to sell it, and buy a stand alone DP to practice my piano on.
And while I suspect most will disagree with me, I found the action on the Casio PX870 to be far better for me than the MP7, and have had it for a few weeks now and am very happy with my purchase.
I must have a non weighted keybed to play my synths and organs on, so just having the NI 88 would be no good for me, as I would also need a separate keyboard to play the synths, hence I would be browsing and editing on one keyboard while playing on another. So for me, I don’t quite understand the NI 88 note market (sure NI have some nice pianos, but the only real point of their keyboards that I can see is the ease and editing of their synths etc)
However from what I read on NI forums, the people that have got mk2 88 are very happy with the feel. Was just going to quote one of their threads and saw that you started the thread
The only complaint I see is people complaining that NI still haven’t released the name/model of the keybed used in it, and a few people saying they won’t purchase until NI do.
So see what it feels like to you.
I know I will be happy with my PX870 for many years. The thing is, it’s easy to read forums such as this one and convince yourself that as you haven’t got Kawai etc, you must be missing out, playing on a sub par keybed, making your practice harder etc. Sure that’s probably true on some keybeds, but I spent a while in a shop with numerous DPs from all the leading brands, and while if I had another few thousand to spend I probably would have bought something different, the PX870 felt the most comfortable for me (I tried Many other makes and models) and that’s all that matters.