I have had Sytrus since it was launched and find that I use it more and more in other applications than FL Studio. Recently I use it in Ableton Live 4, but sadly there is an incompatibility problem which Image-Line promise to fix "soon". But apart from that I am having a great time with this synth.
A reviewer below thinks it sounds bland. I couldn't disagree more. I own Absynth 2 and while I don't think (as some do) that Sytrus is an Absy-killer, it is most definitely a synth with incredible capabilities. Editable waveforms, multiple oscillators, grid FM control...a lot of thought has gone into the making of this app.
Image-Line's price policy is that by pricing this higher than their other stuff it will appeal to more people. I don't know if that works. $179 is not "cheap", but for a synth with capabilities like this it is certainly not expensive. Still, I wonder if buyers will not look at the slightly more expensive alternatives like Absynth and Z3ta.
But for those who feel a bit adventurous I highly recommend this synth. I use it to create synth patterns in jazz/fusion music as well as some endeavors into electronica, and it works great in both genres.
Graphically it is a stunner - my biggest gripe is Image-Lines stubborn "small font" interface policy - it is hard to read some of the text under buttons etc. Also, a lack of a decent, printable manual is a problem for me since I am sick and tired of wading through HTML help files. I want a manual to read in bed...
Customer support is no problem. Image-Line is a responsive company and I've never had any problems with them in any way.