Whilst the non-standard administration via instances takes a little while to learn, once you've done so you're left with a really well built extension with some superb configuration options.
The price is a fair one, I've yet to test support, but from what I've seen so far I'd recommend this without hesitation.
The look 'out of the box' is very good, the performance equally good, and the configuration options are comprehensive.
Support is top notch too. Which for a free extension is well above the call of duty.