I really like the La Sportiva no-edge shoes, but without a women's-specific no-edge shoe (until now!), I had a terrible time finding a good fit. The Maverink fits me quite well since it's basically just a rubber sock, and they were relatively cheap, so I'm overall pretty pleased. However i don't think this is a shoe with mass appeal.
The Maverink is a squishy, soft, sock-like no-edge slipper. You have tremendous sensitivity and you can kind of glom your toe onto the weirdest looking footholds and then feel that it's successfully glommed. It also kind of trains you to climb more precisely with the point of your toes rather than the front side of your foot. Plus, it's comfortable and not detrimental to wear for long periods of time, like when you are say ARC training. That's really what this shoe is meant for---training.
This shoe does not really help you send: it's floppy, fails to drive power to your toes on the steeps, and doesn't provide any support during technical (sm)edging. (Your foot muscles will have to do this all by themselves.) Regarding heel hooks---it's a slipper, 'nuff said. I bet they do rock on friction slab but I haven't tried it.
Having owned Futuras before these, I also have to say that the no-edge rubber holds up forever in the gym (and these shoes are pretty inexpensive), but it's easy to rip a chunk out of the toe on a sharp nubbin or crystal outdoors and instantly destroy your shoes.
Overall, this is a fun shoe, but I don't think that most casual climbers will have a use for this shoe. I think it most benefits climbers who want a comfortable training shoe to avoid foot pain caused by prolonged wear, but who also want a shoe that helps develop their technique and strength by making things "harder". I believe it was designed for climbing team kids and they now make adult sizes so the big kids can have fun too.
For sizing, I went with roughly my street size and the same size that I found fits in all other La Sportiva shoes; maybe consider also trying .5 size below your street size. Your toes should be all the way to the end of the toebox and maybe just a bit curled in these shoes (you need to eliminate dead space in the toe for the No Edge to work right). I have been wearing them in the gym every session for about 3 months and after break-in they have remained a consistent size/fit.