Been playing slots for a while, here's my feedback:
Start/Stop feature is a bit annoying as the adrenaline builds up on the expectation of not knowing when the reels will stop.
Each reel spinning at a different speed makes me dizzy.
Layout is quite slick, but there's too much information to the left and right of the slot, I would have a tab for the payout table on the bottom menu and put the jackpot pool info on the right hand side.
Lastly, I would have one color for website background and another one for slot machine background as it is currently all white.
Obviously, just my opinion as a gambler, hope it helps.