I think this looks very cool. Definitly usable.
In general I think the uppercase should follow the lowercase more when it is possible.
I would make the bottom of the "E" like in "C", to get it more fluent.
I would find another solution for the "S", it looks a bit affected...
Try connecting the "K".
You could try something like in "Z" on the "Y".
And maybe make the whole thing a bit bolder...

Cheers!

Thanks for your comments Tobias. Here's an update:

Thats right. Now the only thing i can think of to change is the tail of the Q, which doesnt fit the "grid". Maybe it could be a horizontal stroke, not connected. Perhaps also stick to just one type of W and S in lower- and uppercase..
Don