I like that they are very communicative, which makes working with them easy! They will make sure you understand what your options for payment models look like before moving forward too far in development or production of an app/product to ensure it meets their needs as well yours.
Sometimes there was more info required than we were able (or willing) to provide upfront so some things took longer but overall process went smoothly from our end - just be prepared for this when starting out if possible because otherwise you could potentially waste time by trying something different only find out later down the road how much work would have been saved had you started off correctly :).