The animations, music and general love of the source material really shine through in this game and helps elevate the Mother 1 experience into something new and fresh. The general progression path and overworld map layout is loyal enough to the original game, but there's so much new content like new battle features and completely reworked dungeons that (as the description posted here says) this game is clearly more than just a remake. I particularly liked all the new puzzles and the end boss fight in Duncan's Factory, it's a great ending to a new chapter that clearly got a lot of time and effort put into elevating what really was a pretty generic dungeon in the original.
Honestly, my only complaints with the whole experience had to do with some frankly cryptic progression hiccups at parts that either forced me to do a lot of backtracking or occasionally consult a walkthrough. But that's not really the fault of the Mother Encore devs here, all of those moments were decisions that were made in the original NES game. It's easy enough to get hints since the same basic overworld guides for the NES title still work for Encore.