Yes, it is surprisingly polished. I tried playing the first three Phantasy Star games, but each time was put off by one annoying design flaw or another (such as the camera not being centred in II, so that you can't see very far ahead when exploring). In the fourth game, everything just works.

Just about the only annoying flaw still left is that it's not obvious what items do, and you kinda will need to memorize lots of random names... (Well, or have a reference near you while you play) This is actually mentioned in the interview as them not wanting to be too explicit about what things do (not saying "attack +20" etc.) - unfortunately, it's one of those design decisions that does create friction for the player.