Sorry for not being able to timely respond. Even though the sale is over, I'll give you my two cents, in case it goes on sale again.
This library is definitely worth picking it up if you can find it at the price point it was at, or lower. It has a staggering amount of control over sounds. You can use it as a straight ROMpler and play the patches, or tweak to your heart's content and blend in the formant sounds to the degree you like. The ARP section is amazing, per note, and has great arp presets, too. The FX section has 8 slots and blendable sends for mod FX. The amount of tweaking you can accomplish is awesome.
At first, I was very underwhelmed by the stock sounds/presets. They seemed harsh/spikey and too pad focused. While I like pads, it wasn't doing it for me as a stock ROMpler. I immediately set out to try to make some more staccato formant synth type patches. A little tweaking and I was quite impressed. You can also make great undulating pads with the formant feature; very cool.
I haven't had much chance yet to roll my own sounds, but did import a Tuvan throat singing sample I had via Simon Stockhausen, and that was a blast to tweak with the formant tool and the synth overall. I think this thing will shine when I use it with whatever sounds I want. I'm still very much a learner as far as mapping in Kontakt is concerned, however.
A rocking value for 73 cents.