I've dated Christians (both Catholic and Protestant), Muslims, a Jew and a Buddhist. Day to day issues nothing too much of note that I can remember.
Ramadan was a minor inconvenience as I woke up at 3.30am to make her breakfast before going back to sleep. One ex tried to get me to buy 1/10th of a cow ($60) to be sacrificed for Eid al-Adha, but I politely declined that one.
Another time with a different ex I didn't have any wine in the house for Shabbat and after trying all of the local shops the closest substitute I could find in the local shops was a grape Capri-Sun.
Getting woken up on Sunday morning as someone prepares for church was imperfect too.
That's about the limit of day to day things I can remember, so obviously not a big deal.
The only issue, which is a pretty significant one, is when it comes to thinking about having children. This requires flexibility and a willingness to accept that the child will be exposed to 'both sides of the coin'.