I haven't seen anything that interacts weird on the player side. It should be seamless. Most of the changes amount to changes in the specific immunities and resistances given (usually to be more forgiving to the players) and changes in how some copypasta attack routines like Constrict and Gore work (they are now usually baked into the base attack or Multiattack), which doesn't interact with PC abilities hardly at all.
Above CR 11, you might see some paradigm differences. But since moving up +/- 3 levels on the Challenge chart has almost inconsequential effects on XP in practical terms, anyway, that also doesn't matter. I'll bet you couldn't tell me offhand if CR 15 is 13,000 XP or 20,000 XP, and it's pretty plain that one monster in particular giving half again too much XP, or not, is not going to affect most campaigns. The dirty secret about Challenge is that, as vague as it is, it's also not that important to be very precise.