This cover is extremely thin (because of elasticity), so things that stick out on the top of the keyboard (i.e joystick) will clearly be seen as protrusions -but that won't damage the cover, though. But even the cover is very thin and quite stretched, keyboard elements (keybed, etc.) can't be seen trough -which is good, of course.
Cover can be used fine with cables connected on the back side, however it will look nicer, if L-shaped jacks are used. Anyway, cover can not be used with headset connected on the front side. I mean, it would look bad and probably damage the cover over certain period time.
I couldn't find the info up to what temperatures it can be washed, though. But being very thin synthetic, I guess up to max 40°C is ok.
So, is it worth the price? As for usability, the answer is definitely yes, but time will tell about durability.
Just keep in mind, that it only protects again dust and fingerprints.