We have about 8 of the cute little boogers, they're pretty low maintenance, just make sure that you offer them places to hide from the betta.
They do well in a planted tank, with driftwood, and they're a schooling fish, the more of them there are, the happier they'll be. They're also timid in nature. If there's even the slightest conflict over food with another fish, the cories will flee. They also like swimming space up in the midwater zone (where your betta usually hangs out)
We LOVE our pygmy cories, they're so cute, and entertaining. But they frequently make themselves scarce. So you may or may not see them all of the time.