I like the look of the slot machine. The dithering in particular is very nice, and the lights are fun. The grayscale gives it an almost industrial feel which I personally like.
I'm sure most of the feedback I could give here wouldn't be particularly new or surprising information. It's a little difficult to keep track of my score and slot results, the slot position changing at the end of the spin, etc.
If the text could be resized to match the pixel size on the machine, I think it'd complement the look of the machine nicely.