No, other recent games are definitely lower in difficulty, especially TP and the DS games. SS stepped up the difficulty in combat a lot, so I found it much harder than recent Zelda games.
As far as 100% goes, I did manage around 90%-ish without help. I found all the crystals easily enough (just look around Skyloft for the thought bubbles) and I only missed 3 heart pieces (Gorko's, the one at the back of the Sand Ship, and the mine cart mini-game's).
Puzzle-wise, the game is maybe a bit more difficult, but really not much more. Most Zelda fans are used to how puzzles work and are able to figure them out relatively quickly. I found no puzzle too difficult in this game.
SS is definitely not the easiest Zelda.