Gryog was both hard and easy. If you could jump out of the water perfectly, it was a breeze and possible to avoid taking any damage or even more then like 40 seconds to fight him. But he punished mistakes pretty harshly and if you didn't do your jumps just perfectly, you would almost certainly pay for it.
I would say I AoL in that i pretty much just gave up on the boss at great temple, i didn't have it in me to walk back thru all of hyrule, multiple times to get to the great palace again. Sure if you just game over and restart it puts you there, but if you decide you wanna take a break then no dice. After a few failed attempts I just decided I dont' care lol. If i actually could restart back at the palace when i turned my DS back on, then ya I would have probably beaten it already. Could just use the sleep mode i guess, but meh.
Hard for me but easy for others? Maybe the frog singing mini game in OoT, where you had to play the ocarina to make them jump, that took several attempts for me. I guess any boss in TP also counts as too easy.
Hard? Sailing in WW, not hard as in difficult really, more in that, I don't want to fight sea monsters or jump on barrels to get rupees, can't i just sail in peace and enjoy the ride.
Oh i know majora's mask, swamp shooting gallery, that thing required perfection, and usually takes me several tries to get past when ever i do it.
Hard for me also is Desert Wasteland with out Lens of truth in OoT (I like can't do it), there is like no land marks to judge where i really need to walk, Majora's mask under water is easy cause you have the signs to know where the turning points are.
Now things i think are easy that others find hard? Gerudo Horse Back archery, thats pretty much first or 2nd try to beat it and get the prizes.