At Ungood's suggestion, I decided to have a look at DDO. Yes, it's more than 14 years old, but I had never played it before today.
One of the first things I noticed is that the interface is tiny. That is a relic of the game's age to some degree, but the engine wasn't built to scale nicely to higher resolutions. That said, it does at least work properly at 4320x2560 and without needing to do some messy debugging, which is more than can be said for some games (e.g., Trove, Elsword, Aion, Pagan Online).
The graphics are pretty dated. The art style reminds me more of EverQuest II than anything else. Thankfully, the game does not suffer from EQ2's awful animations. Graphics that are rather bad by today's standards is not a deal-breaker for me.
From digging around, it became clear that the game is incredibly complicated. Some MMORPGs want to offer a streamlined, on-rails experience. DDO is having none of that. They give you enough rope to hang yourself, though they do offer a decent initial tutorial and advise new players to go with some default builds until they're familiar with the game.
It looks like the game has an enormous amount of content, which is what you'd hope for from a game that released 14 years ago. Also importantly, the game has added to its content and not deprecated the old. That's the key point that Ungood made on another thread that led me to have a look at DDO, and I'm pleased to see that it's accurate.
As a lot more content has been added at all levels since launch, if you do all content for a given level, you'll earn vastly more experience than it takes to level up. And that's to say nothing of doing the same content at multiple difficulty levels. Fortunately, you don't automatically level up just because you have enough experience. You don't level up until you choose to do so. That allows you to do as much content as you want without the game forcing you to level past it the way a lot of other MMORPGs would.
The game is "free to play", with vast swaths of things stuck behind a paywall. You can buy things piecemeal, or buy a VIP subscription that gives you most but not all of the stuff in the store. I'm generally in favor of the subscription approach, though I'd like for it to be more all-inclusive.
The game does let you have an ample number of character slots. A subscriber gets 11, and you can buy up to 30 more. That's a big deal for someone like me who likes to play alts.
Playing with a controller is somewhat awkward but not terrible. It's not yet clear whether a larger number of available skills will become troublesome to use as you get higher level.
The game's content is very heavily instanced. As best as I can tell, the only areas shared with other players are non-combat areas. Still, instancing has its advantages, as it allows nearly all content to be done either solo or group, and scale to the group size. In addition to group size scaling, it also has adjustable difficulty. That doesn't make grouping completely redundant, however, as the max group size is six, while instances won't scale difficulty to more than four players. Thus, a full group of six is effectively playing on 4-man difficulty, which should make it easier than soloing or smaller groups. That seems like it should make grouping more important as a way to take on the higher difficulty levels.
The combat is advertised as action combat, and it more or less is. It's not the fast action combat of Spiral Knights or Kritika, but it is a quicker pace than just about anything that isn't advertised as action combat.
On net, it looks like an interesting game. I'm glad Ungood brought it up in another thread as an example of an older MMO that would readily let new players pick up the game today.