It's been a while since I played without. (Actually my last pre-Old Gods play through was quite a while back when it was either vanilla or very light on the DLC) But from what I remember, and what I've experienced recently, and what that wiki page has reminded me, I'd say that yes, the Revolt system in Old Gods is much better. I'm not sure if it's more realistic, as the revolters just sort of get handed a few counties and it sort of happens out of nowhere most of the time. Just a random event or pushed in the background, unseen by intriguing enemies. This seems a bit odd to me, but from a gameplay perspective, it works. It actually gives you a reasonable foe to fight rather than the old way of just the occasional scattered and weak army which were more of an annoyance than anything else unless you already had too much on your plate to deal with.
Also allows you to take advantage of revolts happening to enemies a little more as well, since it is a bigger issue for them as well. My latest 700 era unification of Sweden was very much helped out by a neighboring large tribe having a revolt happen which weakened them enough for me to swoop in and gobble them up.
Still, where old gods really shines is if you decide to play a pagan viking faction. I'd played them before, but it really does help out quite a bit in making them viable powers rather than hard mode challenges. Supposedly it's good for other pagan factions outside of the vikings as well, but I'm less adventurous there, I play what I know (or have a vague idea of anyway)