Not everyone is going to get the hang of up/down, side-hill lies at the same time, right away.
I believe Sega Genesis Golf had side-hill lies that a player had to compensate for. It wasn't all that bad. Its about starting the ball on the right trajectory towards the hole. The distances everyone is used to should remain the same.
My question is, will the side-hill lies feature be the new way the game plays, or does it have an on/off switch? Just curious.