If you're looking for a do it all, fully featured, hammer action midi controller, this is the one, with a very important caveat. The KeyLab 88 is solid. It's metal, it's heavy, and the build quality is amazing. It's also quite a beautiful piece of kit. Arturia really thought of everything with more inputs and controls than one might think of. The sheet music stand (great for the iPad) and the little shelf for the computer are the simplest of solutions that just work. I don't know how no one else thought of it before. Very practical.
One thing to consider is that the keyboard is heavy. If you're traveling with it from gig to gig. It's something to consider, though it should also take more punishment with its metal construction. If you're using Arturia's Analog Lab, it's perfectly integrated with that, as well as with every popular DAW available. It comes with some magnetic label cutouts that work really well and adapt to whichever DAW you prefer. It's yet another simple solution that just works. As it's a fully featured controller, it pretty much works with everything, though, obviously, like the NI S88, it's fully integrated with their own solutions.
The one caveat is the heaviness of the keys. They're heavier than other keyboards, including those that use the same fatar keybed. One gets easily used to it, if you're used to playing on heavier pianos, but it's an important thing to consider when purchasing this keyboard. This might also make the key response seem a bit sluggish, but this all depends on your personal preference and whether or not you get used to it. I don't find it's an issue, but understand that it's something to consider and everyone's experience and preferences may vary.
In summary, this is an absurdly complete piece of kit at this price range, and it certainly works for the studio (I prefer something lighter for travel). As hammer action MIDI controllers go, you can't go wrong with this one, as long as you're happy with the caveat.