Its a good fun dice roller and is pretty complete at the moment.
Its visually okay: readability is a little weird because everything is white on blue, one can't distinguish between × and + easy. Maybe every type could use a smudge of colour. And extra round adding rounds as it being pulled, not as it being played like the rest of the cards can pull one out a bit. I think the fairest approach would be just a button appearing, offering to end early, but yeah, don't see a scenario where not playing your deck would be beneficial. Right now if you grab good stats early, you shoot past the goal and get transfered too early to use the whole deck, just as you mentioned.
Still, it's a thing and it's addicting. Gamespeed option would be great, I want to gamble faster!