Needs AI opponents.
A shame really, because it's a good concept, if a little confusing to get the hang of in the first place. I like the way that it looks and I can see that over time, this will become a very addictive little game, if it's developed from here.
Perhaps have an interactive tutorial, as opposed to the instruction book at the start, which was utterly confusing, even to an experienced card player, such as myself. You will pick these games up much better, if you play them and have the rules explained to you, as you need them and play alongside them.
Decent colour sets, decent sounds, perhaps a little thing in the layout could indicate which cards you need to click to finish a trick, just to make it more user friendly.
[Review Request Club]
I'm not sure what you mean by AI opponents or 'finishing a trick', so I'm not sure why you only gave me a 3/5 on this. The tutorial could have been explained better, I'll admit that. I'm not very good with the interactive thing, but perhaps an animated one would have worked.
I was at one point considering making a multiplayer version where you and an opponent took turns trying to score points and prevent the other player from doing the same, but i definitely don't have the skill to code an AI that will play cards strategically.