I love the Advantage rule in 5e!
I’ve always hated dice pool mechanics since they obscure the actual probability compared to something clean like percentile or a straight d20 roll over. But after working with ad/disad, I’ve found that it’s great because it’s so backwards compatible with all of classic D&D, it just slots right in.
It’s also… coming from 3e (and, worse, GURPS) with all those messy modifiers to keep track of and stack, with ad/disad it’s like fate is setting your bonus. Should “trying to shoot someone while it’s raining and the mud is slippy” be minus three or minus five or minus seven? It’s just disad. Fate sets your bonus. If you roll an eight and a fourteen, well, then that means fate gave you a -6 to that roll. I as DM didn’t have to decide!
It’s also a bonus that scales very well with your skill. The bonus is big when you’re at an average skill level but becomes smaller as you move towards the extremes of high skill or low skill. That’s pretty nifty.
My main argument against dice pool systems is that it’s very important that module designers and rule designers understand the probability of their systems and with some of these dice pool games, it’s obvious that they don’t. But advantage has already been “thought through”; even if someone doesn’t understand it, they can’t muck it up too bad. The naive view of “it’s just like giving them another shot at it” is fine most of the time!
The formula for success with advantage is 1 - square(chance of failing). For example, +0 vs DC 11 is 0.5 chance of failing on one roll, so it’s 0.75 chance of success with advantage.
I haven’t gotten to the best part yet. Speaking of fate, the game called “Fate” taught us the value of having a rules system that can handle any diegetical element. Thorny bushes, burning clothes, flipped bookshelves, fighting out on a plane wing that’s slippery and moving… ad/disad brings that to D&D! We don’t have to stick to a codified set of conditions and modifiers when we have the life-changing magic of ad/disad at our fingertips.
It’s not about being the best thespian or wittiest wordsmith—Exalted and Wushu comes to mind as previous stunt systems that failed (for me)—instead, just engage with your environment and you’ll get advantage!
I actually dislike the Faerie Fire spell (as a game designer, that is—as a player, it’s a perfectly good spell to take and use) for that reason. I want advantage to be reserved for conditions, and ad hoc shenanigans, and inspiration (a.k.a. canned&preserved ad hoc shenanigans).