I thought there'd be more reviews of this one, which maybe shows how the 303 is going out of favour with the dance crew.
And that somes Claw up really - it is designed as a 303 clone. Does the world need more 303s? Well, if you like that sound, then short of actually shelling out and buying a real one, this is the next best thing. To my ears it is THE most realistic 303 plugin. I have Rebirth, and I now use Claw in preference (even though I don't use it that often - after all, you can't have a 303 in everything). I used to own a 303 way back when, so I know what they sound like - Claw gets that difficult to obtain lemon-sucking edge when on pulse wave and filter down, which is the real test of a 303 clone. It can sound very hollow but also has the true 18dB/Oct Curtis chip squelch.
A very useful addition is the hi-pass filter to obtain that hollow sound. Without it, Claw can be just a little too bassy. And that is actually a bonus - with one flick of a switch you get 303 squelches that sit ideally in a mix. A real 303 lost its bass end with the resonance up. You can do that with Claw too, but if you want to retain the bass content you can - and there aren't many true analogue synths that could achieve that particular trick.
I still own an MC202 (same circuits/filters as a 101) and Claw also does a very good 202 emulation when the resonance is further down. So it's alot more than a one trick pony - sure, it's aimed squarely at the techno dance-heads; but that just shows how ReFX got it right again - they give (for free!) one of the best 303s AND the best 202, all in one package.
There is midi automation, a good set of presets to start you off, and it is very easy to use. Very little CPU useage also. Stable as a rock bolted to the ground.
It won't do pads, it's not polyphonic, but so what - if you do dance, you NEED Claw, and that's what Claw sets out to give. And it does with bells on.