If your partner is into it then it becomes a change from the usual. I wouldn’t want to do it as much as vaginal sex and neither would my girlfriend. But occasionally she suggests it. I prop her off the side of the bed with a pillow under her so I have a great view of her asshole. Spend lots of time lubing her up. When I can comfortably get my thumb inside her ass I begin slowly shoving my cock in. Feels great because it so much tighter than a vagina.