Apart from all the other known issues with performance, crashes and what not, I've encountered the following issues;
It appears to be impossible to shoot off limbs as demonstrated in the gameplay videos on the website. Personally, I think it's a really cool feature, so naturally I set about to try it out.
It took me a while to figure out that you have to hold the aimed shot button down to get the targeting wheel up. Unfortunatly it doesn't seem to do anything targeting the same limb all the time. That - or the visuals effects are missing. So far I've tried with a boltgun and lasgun. No joy.
Also a bit of input, if I may.
The whole activation seems a bit clunky - at least on PC, it may differ on consoles or with controllers. You have to hold the aimed shot control down far too long to get the while up, and when you finally do, it's pretty easy to target the wrong limb. Also, should you get knocked back while having the targeting wheel up, the game client shouldn't use the ability on whatever limb it's targeting as default. Simply just don't fire the ability IMO.
When I started the game first I tried to set up some custom controls to be able to move with WASD. After having bound W for moving forward I couldn't bind the Z-key for swapping weapons for some odd reason; The edit input changed, and appeared to save, but it seems that it just wasn't commited for some obscure reason.
After resetting to defaults, I was able to bind it the way I wanted by changing the Swap-weapon key (W as default IIRC) first and then assigning W for moving forward.
Hope this helps.