No major complaints the few years I've used it. Works well for both emulating old games and playing modern ones. Which is a hard requirement for me.

>not insanely overpriced
>analogue sticks in the correct position
>xinput and dinput support
>bundled software that allows you to easily remap buttons

The shoulder buttons and triggers aren't anything to write home about however. Shame there isn't a triggerless version. God I hate triggers.