I found this game really quite fun. At first I got a bit frustrated because I didn't read the controls properly [my fault of course] but after checking out the way to use items etc, I found myself playing several rounds. Considering how simple it is, it's got some quite addictive quality :)
As far as improvements, I never was able to swap out a spare card and always got caught, since the opponent suddenly looked up without forwarning. Perhaps a sound effect or something that warns that the opponent is about to peek would have made that less fatal. I'd also say that once you know the controls (and if you know how poker hands are scored) the game is a bit too easy.
Finally, I think Aces are 'Low' in this game which I found jarring. I beat a pair of aces with a pair of 4s :P
Good job overall! :)
(Ps: visuals and Sound are mucho nice)