Slate's hardware and software are both excellent. I use all of the Slate software tools, and really, they sound absolutely unlike anything else on the market. Fabrice Gabriel, who does the software design, is simply a genius. He's way ahead of the curve.
As much as I admire, for example, the Waves guys, put the comparable Slate stuff up against the Waves that's supposed to do the same thing, and the Slate stuff really impresses for its greater depth and detail.
The hardware also sounds great; the compressor in particular is a very, very nice take on the 1176 style of compressor.
Slate himself seems like quite the character, definitely a hard-charger. Gotta admire his ears for good products.