I can't say enough good things about SonicSynth. I have spent the better part of my time since I got it experimenting with the soundcontent and the ideas it could give me. Bottom Line: I would buy it again just for the Pianos and organs. The different acoustic and epianos (that tremolo rhodes is mouth watering) not only sound great but sit just perfectly in a mix. The organs go from shimmering chorus organ (one of my faves) to the Jon Lord screaming B3 sound. The strings have a lot of "feel" to them, especially the ensembles. As I use Sonic Synth more and more I keep finding new patches to use that simply amaze me. The SFX patches are an example of that. Very atmospheric and brilliantly done. The pads, synth leads, basses and msic synth banks are probably among the more heavily used banks for me when I sit down to work at ideas, as they inspire me a lot. The Wright Lead is very quickly becoming one my favorite Sonic Synth patches, and anyone familiar with my posts in the Cafe is already aware of the heavy use of Sonic Synth pads in anything I do.
Frankly, if someone asked me which VSTi they should buy if they could afford only one, my answer would be SonicSynth (unless the person is a sound-mangler of course). SonicSynth makes me want to run out of the door and buy a more expressive controller than I have right now.
I don't think I can really add to the reviews that have already been written. SonicSynth is worth the hype, and Squids and Co's great support is already well known around here.