Excellent controller, very small and compact with huge capabilities.
I use it in Bitwig Studio and I have to admit that it works perfectly with the associated script (available on github). With EC4 you can control literally everything.
It is well designed and durable, the encoders are excellent - the spacing is just right and I personally prefer the slightly "sharpened" encoders on top. The push encoder function is also great. The very good thing is that it has an OLED screen which is top notch - EC4 is very easy to program thanks to the OLED screen.
Faderfox controllers are a bit more expensive, but the quality is worth it.