Holiday Memories heals 20% of your max HP and blocks 100% of Dark, Physical, and Fire, once per battle. It's an interesting Healer that could be quite useful, but the 20% heal isn't as great as say, Feel Better Soup's 50% heal. Feel Better Soup, as a refresher, also blocks 100% air when it's used once per battle.
But, if you're up against an opponent that uses Fire, dark, and physical and you don't have a better healer, Holiday Memories isn't bad. Especially if it keeps you from taking damage from those icon types on the turn you use it to heal. Also, Fire is one of the harder icons to block, as fewer items do it or block great quantities of it. So Holiday Memories would get a point for that too. I would stick with a 50% healer, but against the "right" opponent, I can see it being somewhat useful.