Quite late, but yes, Didi works with foreign credit cards. Although my Didi account is tied to my ICBC US UnionPay card, I have registered non-UnionPay cards with it before. The downside though is that you can only register one credit card at a time. I've only used Didi in Shanghai and Guangzhou, but in both instances I found my drivers to be generally pleasant and capable of coping with my halting command of Chinese.

Another frustration with Didi is that while you used to be able to charge driver tips to your foreign credit card, this is no longer the case, and you'll need to tip them using Alipay, WeChat Pay or some other local system. I usually use Didi on long trips (like hotel to PVG), so I don't tip, but on shorter trips if this continues to be the case I'm going to start handing a cash tip to my driver to go around this, given my own troubles with trying to set up an Alipay or WeChat Pay account.