I played Ascension way back when, and it was awesome. It's basically a glorified killing arena, which means the action starts early and keeps going all the way to the end. No boring laning phase, no cs to try to last hit, no worrying about who's going to support, none of that crap. You pick your favorite champion, and then you teamfight, and then you teamfight, and then you teamfight.
Once in a while you get the enemy team down for a few seconds and you can take points or try to beat Xerath and get ascended, which is basically a buff that makes any champion into a raidboss. Killing Teemo has never been so fulfilling.
Of course, since the winning team is determined by which team gets X amount of points first, you can still make a comeback if your team is constantly losing teamfights. It's not easy, but it's sure as hell a lot more of a chance than you'd get on the rift these days.
All in all, if you like the slower burn of SR then Ascension probably isn't for you. But if you like non-stop action like Dominion or ARAM, then Ascension is pretty sweet.