For reference, my hand's 19x9.5cm
I've only had my Thorn for a few days, so this is more of an early impressions review. To start, the build on my unit is solid. No creaking, no flexing, nothing feels loose. The coating on my white version feels nice and grippy. My hands tend to stay pretty dry, but I tried putting a little moisture on my fingertips and it felt even grippier.
I'd say the clicks are alright. I prefer the feel of mechanical switches, but for opticals I'd say the clicks are pretty good. The side buttons are on the larger side and stick out from the body more than usual. I actually like that, but I know it may be off-putting to some people. The skates are pretty good for stock skates and I haven't felt the need to change them ought yet.
As for the shape ... this is the first ergo mouse I've spent more than a few minutes with, so I can only really compare it to my experience with ambi mice. Compared to my Beast X 8K, it feels a lot more bulbous in the hand, both taller and wider. It's clearly intended for a claw grip. I get a pretty comfortable relaxed claw grip on it, but I can see it working really well for aggressive claw. It's got a fairly high mid hump that I find really locks my grip in place and the contours on the sides fit my hand nicely. The trade off for that locked in feeling is having to get used to having less vertical adjustability, though, which is something that took some getting used to. I'd say given it's size it might be okay for an aggressive claw for larger hands and its bulkier feel would probably be good for a smaller hands to palm.
As a first ergo mouse, I'm liking the completely different feel from my other mice. I'm still not sure if ergos are for me, but I intend to give it some more use to find out. Quality-wise it's great, so if you're like me and are looking to given an ergo a try, the Thorn seems like a pretty good choice.