Meh, my answer is I have fun RPing with people that are fun to play with. Is DDN specifically as a game adding anything to that? No, frankly. There is nothing particularly bad about it, but DDN is not a lot like older editions, mechanically and playstyle-wise it isn't all that close to AD&D, and it has none of the "lets go back and write coherent rules" aspect of 4e. Honestly it feels like a hodge-podge, sort of a revamping of 2e with about 100 writers that each got to add one feature until it became a teetering heap of near-incoherence.
The magic system is obtuse by comparison to any other edition. There are sort of random subsystems tacked on. For instance my 2nd level cleric had 3 spell slots and could prepare 3 spells. So he could cast any set of those 3 spells (IE he could cast CLW 3 times, or CLW 2x and Bless once, etc in any combination that he felt like as the day went on). Beyond that he had several cantrips (due IIRC to his choice of deity) and another 'permanent' spell (Command) which he could always cast once a day. On top of this he had Channel Divinity, which is basically ANOTHER 'spell' system where you get 2 effects that you can use once per day each, the exact effects varying depending on your god.
The actual spells could be of various types. Sometimes they were 'power words', which apparently meant they could be cast along with another action. Heals could also be cast along with an attack. There was also a 'maintain concentration' thing, which meant certain situations could disrupt durable spells like Bless. My character also had a "use Lance of Faith as a reaction" so he could blast things whenever someone attacked him.
The result of all this was that the action system in combat was both at least as complex as 4e, but also a LOT harder to understand. Other characters were equally festooned with options which worked in a number of different ways (and at level 6 my character would have added martial dice too). While it would be overstating the case to say someone like me that has played for 35+ years in RPGs would have a LOT of trouble figuring out these rules they were to put it bluntly far inferior to the action system used in 3e and 4e. I found the AOE system used in DDN to also be inferior to 4e's system, as it was considerably harder to figure out but had almost indistinguishable results. In a case where you would not use minis it would hardly matter anyway, as who was hit would be strictly up to the DM anyway.
I also found the whole skill/check system to be fairly cumbersome in practice. Where 4e's short list fixed system was quick and effortless the DDN system required more decisions and always provoked questions at every turn about what might be checked for. The constant questions about advantage and focus distracted from play as well.
While I think the advantage/disadvantage system by itself might be a good idea I think its combination with open-ended skill lists and the "use any ability score with any skill" impeded fast play to little overall benefit. I found myself wishing for the 4e skill system pretty quickly.
I find it 'worth playing' in the sense that I like to play games. Would I PAY for DDN in its current state? NO. 2e would work as well, I already own it, and it is a simpler game, though DDN's rules are slightly more coherent in some ways. Overall the game doesn't feel like a cohesive design, is DEFINITELY slower and clunkier in play than 2e, and yet lacks the clean design of 4e and ease of explaining it to new players. The attempt at making a simpler action system was an especially glaring failure as I couldn't help noting that the various types of spells and 'powers' interactions would have been instantly simple to sort out with a standard/move/minor/free action setup.
Honestly, my recommendations to the designers would be:
1) just go back to the pure Vancian magic system, you know you want to and the thing you have now is a hot mess.
2) put actions back in the game, they are simpler.
3) Cut it out with all the different forms of 'spells' or 'powers'. Just make one type and stick to it. I have no desire to learn the rules for cantrips, spells, expertise, and channel divinity, that's ridiculous.
