Hard pill to swallow for the hardcore enthusiasts out there: this game was only the best of its time because what we had come to expect from video games at that time was so much more forgiving than it is nowadays.
The combat system is an unwelcome relic. Hitting a hotkey should cast the spell, not set the spell to right click, which can only be described as clunky and cumbersome. Also, simply spamming one ability repeatedly until things die feels a bit mindless and boring.
Endless farm runs of the same content over and over is not good.
The reward system is trash. Assuming online trades starts to make it ok, but not when you realize that somebody with a slightly better ping than you gets the loot and you get laughed at on that 1/6000 time that your desired piece actually drops.
Single player deserves a better reward system to make up for not having online trades available, but nah.
Ok, so that was a lot of bad, but there is certainly some good.
The mood hasn't aged a day. It's graphic and violent horror goodness. The graphics update looks really nice.
A good chew on the member berries until you remember what "end-game" Diablo 2 actually was.