the most active multiplayer for such an old RTS, there are custom community-made servers with anti-cheat measures
Blizzard classic games department is currently working on the update, some months ago they released a comaptibility hotfix and are currently working on more extensive update that should touch up all aspects of gameplay even though new ingame content is unlikely
massive custom map scene creating total conversions and new gamemodes, some of which (for better or worse) became their own genres
graphics look okay even now, the more stylized bright graphics aged pretty well
Campaigns feature custom units, scenarios and other aspects, but whereas Starcraft 2 gets it more formulaic with pretty obvious pickup placements, WC3 has more interesting secrets and challenges unrelated to the main objective, baseless missions are fun dungeon crawls
Unlike SC2 you can play MP with pirated copies
Custom maps? They are VERY diverse - singleplayer maps, singlepalyer campaigns, competitive multiplayer, co-op multiplayer, altered melee with standard gameplay but different races, dungeon crawls, RPGs, GTA-esque urban living simulators where you rob banks and spend cash on hookers, puzzles, adventures, entire new settings, recreations of other games, competitive action arenas where you use combined spells to push enemies out, survival games, actually fun ASSFAGGOTS like Naval Battle, minigame collections, 4X grand strategies, other goodies
Defense of the Ancients was inspired by Aeon of Strife for Starcraft 1 that was inspired by Herzog Zwei and Future Cop LPD. Even if it wasn't for Warcraft 3 ASSFAGGOTS would have happened anyways.
Also, I'd say the use of heroes as they are in Warcraft 3 is pretty justified, with the current approach to RTS that lasted since the beginning the early game is usually pretty dull due to the need to build up the economy and military is extremely limited, so heroes add some depth and even if that means active sabotage of enemy economy becomes a viable tactic. I wish we would move away from this whole early game concept anyways, like you start off with a base based on your preference or something, but whatever.
If you played all three LotV might feel quite formulaic by now, atleast some missions, but the new units Protoss get, and General-esque global abilities, are super awesome. Also writing is way better than HotS because HotS was the low point in SC writing, unless you really hate the premise of protoss getting rid of this "mysterious dogmatic aliens" by abandoning their dogmas, but considering the fact SC2 campaigns are so much more, er, intimate than SC1, so it's kinda hard to keep them mysterious afterwards. Anyways they get rid of caste system because
Rory Swann Karax managed to lead the forces during one of missions well and because nobody but them sues this or something, they abandoned their fear of advanced robotics because they had to resort to usage of Purifiers and they learned they rebelled because they were treated as machines not equals so offer them equality and the robotic imitation of Fenix proves they are willing to treat machine protoss fairly, they destroy Shakuras to stall the Amon's forces, they abandon Khala because they learned it can compromise their entire race and something something.
Anyways go ahead buy it, it's pretty fine and enjoyable.