As this synth is cancelled, the chance is good to get some reduced offers. but even for the original price i definite recommend this synth(s) to everyone! Some ensembles of the included libary are worth the price alone f.e. vierring or greenmatrix. Yes, the libary is very good equipped: it has subtractive, wavetable, additive, physical modelling, granular, more or less fm, sample player and so on...!
GUI: i like it lot. I think this is how a "COMPUTER"-GUI should look like: not that mega 3d-orgy, great mouse-support with f.e. the often used xypads, a nice "scientific" look, drawable sequences, lots of windows where the audio-output is graphical displayed and a good overall layout for the workflow.
Sound: The reaktor-sound is to my ear very balanced and "neutral". The quality is really top notch! What astonishes me mostly are the built in choruses: i would say these are the best i´ve heard so far.
Features: too many to mention. it goes from great midi-implementation to synth-specific peculiarities like attack modulation, different lfo-speed on each voice, lots of tracking options, resonance behaviour and a lot more!
Documention: i think it´s a little bit short. All emsembles are introduced superficial, but there´s no in depth explanation.
Presets: A lot and most of them are good.
Customer Support: For Reaktor Session there´s no official support any longer. But there is a large community on the web, so you have a support from the user´s side.
VFM: 10 points!
Stability: Beside loading audiofiles with the sampleplayer, i haven´t found huge bugs so far.
Summary: If you have a little place left in your sound-arsenal, go for it. It´s one of the best synth around! Actually i have to say synthS!, because RS has many different synthesis in one programm. One last point: NI says, that you can´t build new instruments with RS. but that´s only the half of the truth, cause what you can do in the terms of ni is building "ensembles". That means that you can create ensembles f.e. with more than one synth, free configured effects-chains and eqs/ mixers if needed. So it´s "half modular" i would say, as you can´t build instruments from scratch.