Korg nanoKONTROL Studio

It is overall a very good device, a nice addition to my home studio.
Couple of things to keep in mind.
1. If you are using reaper - you need to set everything up by yourself. It doesn't have a default profile. You can find a reaper profile in the internet, but still, you'll probably need to set up most of stuff on your own. It will take time.
For Logic it does have a default profile, just FYI.

2. The wireless connection is not really stable. The biggest reason for me to buy this unit was wireless connection, but it loses connection very often and pretty randomly. Not sure if it is DAW, OS, or the unit problem. Wired connection works fine.

Ultra portable all-plastic controller. Fits in my coat pocket (I have big pockets) Faders are ok, not bad but not great either, fluency could be better. Pots are decent. Touch pads are nice and responsive.
Great integration in REAPER, you can get some mapping packs at the forums to help you get started.
Downsides mostly the small fader size but that's what you get with going portable. If you want something that will be used as a fixed controller more often than it will be carried out of the house, go for something bigger and just bite the bullet in those odd events where you leave the house with it.