In my opinion, that is not a sutiable size for a Betta.
It's alright, but not ideal.
Also, is there a lot of airspace above the water?
Because it is an labyrinth fish, so it needs to breath air.
Yeah I know. Right now he's adjusting to the tempurature and not actually in the tank...
I'll go back to the petstore for a new 2-gallon tank tomorrow.