On a personal level, I'm very excited to know that I won't have to try and integrate Alipay in any of our products anymore. It's nightmare to deal with, even for our Chinese team.
But for Stripe, it's a huge step forward into tapping in a massive market. Most Chinese people can't (or won't) use card to pay online; they simply have Alipay connected to their bank account or use prepaid cards. Good move Stripe.