Hypersonic is the definitive one-for-all sound and synthesis bank if you're after a bit of everything.
It is a jack of all trades, master of a few. The rich assortment of synth leads, pianos and string sounds really are powerful for any sort of arrangement.
The user interface is good, there isn't much that could be improved and the miniature keyboard is great for trying out presets and the lovely legato/glide mode is brilliant with the right presets.
The sound quality is good, there are some great quality piano and string sounds, and most of them are good quality. The drum kits are of decent quality too.
The amount of features with this instrument is incredible, with legato and glide mode for flawless screeching lead and synth sounds.
Documentation is good, with an emphasis on those who have not used an instrument of a similar kind.
With at least 1000 presets and more if you love mixing sounds for more variation, it really is the most effective instrument for any MIDI arrangements that you want to get sounding right. There is just about everything covered.
I initally had trouble with the copy protection and the customer support was very good and emails were answered promptly with plenty of suggestions. I got it working very quickly.
Overall it is great value for money especially considering the enormous amount of presets and sounds to cover almost everything from A to Z.
Stability is great, it does crash every now and then but crashes are very rare.
A brilliant VST and it's worth every dollar. Even at $399 it is a brilliant concept - a fully fledged workstation system in your PC for a mere fraction of the cost of the hardware equivalent.