Short WebMs can't do DDO's quest design justice. Every single quest feels like an adventure, with a wide variety of objectives, leagues beyond the usual "kill/gather X of Y" tedium that plagues lesser MMOs. From just the Masterminds of Sharn quest chain alone, you're investigating a series of gang-related murders, protecting a tavern from the mob, raiding industrial facilities, and protecting whistleblowers, all tied together by toppling an ultra-powerful inventor with the byproducts of his own invention. Even basic dungeon crawls are well-polished, with sprawling nonlinearity, secrets to uncover, and traps to evade. As for the combat, I initially thought this was going to be another tab-targeting game, where everyone just stands in place, trades hits, and recites an ability rotation, but instead, as a caster, I found it much more natural to hurl rays, explosions, and storms wherever I pointed, jumping before firing off every blast to at least blow up the ground crowds of enemies are standing on, and keeping strong single-target beams for priority foes; it's more akin to a fast-paced arena shooter.
The only major flaw is how much of the game is locked behind a paywall, redemption codes, or cold hard grinding, difficulty levels in particular. DDO's too trivial on Normal for any of the above to shine, and without either paying up or getting smuggled into Elite/Reaper by another party member, you have to trudge through each and every quest at least twice, once on Normal, then once on Hard, before the game starts biting back. Hitting level 20 then reincarnating back to level 1 twice over, New Game++ in other words, is the only other way to unlock Elite/Reaper without spending money. Other anons have claimed each reincarnation takes roughly fourteen hours, but that's if you follow a guide, and I can't imagine most new players, just checking out the game, minmaxxing and guidefagging from the very start. It's more likely that they set the game aside for good after getting dumped in the Harbor post-tutorial, which consists of nothing but drab sewer crawls clearing out kobolds, considered by many to be the weakest quests in the game. That would have been the only low level content available too without GATHERYOURPARTY2025, a now-inactive redemption code that unlocks a huge variety of otherwise-paywalled adventure packs, across the whole level spectrum, among other things. Many thanks to the grinder/VIP anons that let us skip Normal and Hard.
Despite all that, it's going to be really difficult for subsequent games to be better than DDO overall.