Really, really good.
For the price, I am astonished. 5000+ sounds? I have been using this plugin for a couple of weeks now and so far, I am more than satisfied with the variety and quality of instruments. Each and every time I audition a new sound, I am blown away by the realism and flexibility of this program.
Sonik Synth 2 has far more sounds than I would ever need, although it is nice to know that they are there just in case... While each and every sound so far has surpassed my expectations, what really impressed me is the quality of the guitar sounds. I am primarily a piano/keyboard player, but I love great sounding guitar tracks. Beyond that, virtually endless possibilities. SO many drum kits... wow, this is another strong point. Pianos, keys, vocal effects, organs, synths, orchestral, pads, strings, drums, guitars, on and on and on, all sounding equally great and useful.
I will admit, the download and registration process was not as seamless as I would have liked, but now that it is up and running I could not be happier. Seriously, for this price you cannot go wrong. I cannot believe that other, seemingly less useful programs are more $$. Do yourself a favor and get this. If you could only have one instrument plugin, this is the one you want, regardless of your needs.