I've never had any issues with it. It's a really good implementation. If text is too small, just double-click and it comes front and center.
I highly recommend it for travel. Flight time will fly by (pun intended).
Same with me, tapping on things that are hard to see will make it easy to read.
I've played a ton on iPhone, asynchronously vs. real opponents I've never had any problems, have had occasional frozen games vs. AI in 4-5 player games.
Highly recommend the app to anyone who likes the game and plays games on their phones.