I must say these are pretty sweet shoes. I tried out a pair and for overhangs and stuff they were designed for they work great. Very pointy toe is the stuff for small pockets. Fit very well and comfortably new. This is an advanced climbers shoe of course. I thought the heel was decent for hooks, tho it will slip off if really pushed hard since this is a slipper. They edge tollerably well on vert. terrain, tho a bit painful since they have a cambered last. La Sportiva quality.

Just bought a pair as a specialized steep/bouldering shoe. I'm a hard core Miura fan, and found these shoes to be of a similar fit (of course, they're cambered more and such). They run large, so buy a few sizes down from what you normally get from La Sport. I'm a 40 Miura and a 38.5 Cobra.

As for performance, I'm a fan. Power is focused into the big toes, allowing superb footwork on steep terrain. The heel slips more than I'd like, but not significantly more than any other shoe I've used (laced or unlaced).

Of course, this is a specialized shoe for steep face climbing. I still use my good old Miuras for slabs, cracks, and not-so-steep faces.

Personally, I've heard mixed reviews from friends and customers of my local gym. Mainly, with issues residing around how the shoe fits. Of course, just like any climbing shoe, every persons foot is different making trying the shoe on first a must. For me, this shoe is simply amazing. Fits like an absolute glove, making it extremely powerful. Especially when it comes to climbing through smaller hold and overhanging terrain. The shoe just sticks to everything, which is definitely a root from the rubber La Sport uses, and the last from the Testerossa.
Great construction with a shoe that's ready to perform. How can that be bad?

I primarily use this in the gym, it is very soft so it encourages the muscles in your feet to help out. The name follows the other popular shoes in LaSportiva's past, the previous one being the cobra, and the one before that the viper. The newest slipper in the sportiva line is also the viper. This shoe fits very similar to a katana, but should be sized approximately a half size smaller due to stretch. The guys at a local shop thought, before wearing them, that the rubber on the toe would decrease stretch, I have not found this to be the case, they stretch at least a have size, which makes the shoe conform perfectly to the foot. I also have testarossa's which this shoe is shaped to, but due to the lack of any support in this shoe it fits much less aggressively than it looks, or compared to the testarossa. They are a great shoe for steep pocket pulling, the toe is very small and fits easily into small pockets. I do ot like the shoe very much for thin face climbing, they aren't very precise due to the lack of any sort of support, for face I highly recommend either the anasazi velcro, or the much cheaper and uglier red chili spirit velcro, the spirits surprised the crap out of me.