I preferred the way Twilight Princess handled Heart Pieces, by making it take 5 to complete a Container. It allowed us to have a reasonable number of Heart Pieces to find to off-set the high number we got from the number of bosses in the game.
I was very disappointed with the way Skyward Sword went back to 4 Heart Pieces, especially since, with starting on 6 Containers and the Heart Medallions, there were only 24 Pieces in total, the lowest number in the entire series besides Link's Awakening and Oracle of Ages/Seasons. One greivance with TP's Heart Pieces was how many of them were plainly visible and SS did the same thing which just further undermined a classic and usually long side-quest.
I would prefer the series to return to Heart Containers being split into 5. Hiding them better would be a good step forward now but another option would be to have more side-quests and mini-games. I think I'd like that.