To clarify on some of the Warcraft 3 issues;
No clans
No profiles
Can no longer have more than 1 account
No more custom campaign functionality
No more Reign of Chaos balance for the Reign of Chaos campaign
No more built-in tournament functionality
No more The Frozen Throne menu screen
No more LAN functionality
No more offline games versus the AI
No more cross-chat with Diablo 2 players
No more /commands
Removed friend list
Removed custom game filter
Custom game list is no longer global - you can't play custom games with people from other regions
No MMR system
No custom keybinds
Removed the Dryad's "I'm so wasted" voice line, possibly others missing that have yet to be discovered
Cut all the promised new cutscenes
Cut all the new English voice acting
New foreign dubs which are inferior and compulsory, can NOT be changed back
Cut promised new story content
Arthas vs Illidan cutscene looks like cheap fanmade YouTube content
Menu is awful and unfinished with chat clipping
The end of match summary is completely butchered and doesn't tell you useful info
The old client is gone, even if you don't own reforged you're forced into replacing it if you ever connect to bnet
Custom maps now have a report button so blizzard can ban maps and ban people hosting them
And finally, remember that this was delayed before release