It's very good in many ways. The gameplay is fun, deckbuilding is fun.
Some things I'd like to see:
* Better introduction / explanation of things like countdown, objective. Even just having a hoverable tool-tip would help
* Better information presentation, like clicking deck showing the remaining cards.
* Fix some minor bugs, things like the exit (?) button opening a menu where its buttons have no text.
All in all really liked it, and think it has lots of potential if you want to take it further.