Overall, I'm not impressed. Other than the Latin stuff, I think that similar results could be achieved with the current set of kits and a small room reverb.
Yamaha seem to have gone overboard with the drum room ambiance, and unlike Korg's, there's no way to alter the balance of it. Trouble is, there really isn't a way to add this kind of room 'space' around all the other sounds, so you get this disconnect between the drum track and the accompaniment.
Plus yes, I am still hearing some weirdness on some fill boundaries. Yamaha have chosen a much simplified method of making audio drums be able to do different tempos. Most other things that do this trick (Ketron's and many VSTi's) do it by slicing the original audio file into individual component hits, and have a MIDI file play them back. Yamaha have chosen to not bother with this tried and tested approach, and rely entirely on time-stretching the audio file. I think this is what is making some things sound a bit strange, and may well account for the less than snappy fill boundaries.
Kudos for Yamaha for at least trying, but I think they have perhaps jumped the gun a bit with this.
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An arranger is just a tool. What matters is what you build with it..!