The plants only glow about 20 mins. I had several about 7 years ago, they may glow longer now. I got the grass one it didn't have any sharp edges it was cool! Though during the day with the light on the green color the plants are, its kinda weird looking.
I had one of those once, for my first betta.
I liked it, and I always felt it would be nice for the betta to have a tiny bit of light (like moonlight). I have a Sylvania 'DOT IT' LED light that I shine in my current bettas tank so that there's a small subtle stream of light shining in.
She doesn't mind it at all. So I'd get some! I only don't have any now cause I'm using real plants
(Also, have you seen bettas sleep? LOL it looks so funny!)