Ascendant is a great game, with crunch in the right places.
As others have said, the bits that take a while are all front-loaded into character generation, and session time, whether actual combat, investigation, or other actions, is always simple to resolve mechanically. compare the number for the power/attack being used to the opposed value or the magnitude of the problem, adjust for extraordinary effort being used on either side (hero points), roll d100, consult the chart to see if the action was successful and by how much. In my experience it's very easy for a player to sit down for a session with very little knowledge of the system and still make decisions. for example, a player can decide to focus on putting out a fire instead of attacking the villain, and the GM can just present the information as "the fire is X strong, your power is Y strong, that means it will take X-Y=Z time to put it out, which you can halve by using a hero point". in play, you get used to this very quickly.
one thing i particularly like about ascendant is the rules for power stunts. it's good to encourage people to be creative in RPGs; it's also good to have rule framework for how much getting creative should cost, lest someone put one power on their sheet and play like they have 5 other free powers. ascendant starts by asking the GM the unavoidable question of whether or not a given stunt is plausible: light control might easily stunt into heat control, but not into teleportation, for example. if a stunt is permitted, the cost of doing so increases the further the stunted power is from the base power: someone who shoots lightning might be able to stunt into throwing bolts around corners or into reprogramming robots with his lightning, but the latter will cost more points to do. broad control powersets have an advantage here in reduced costs to stunt. someone who is merely super strong is capable of occasionally creating a sonic blast by clapping their hands; if they want to do so regularly, though, they'd be best advised to actually have that power, or else they'll be expending their hero points awfully quick.
[5 of 5 Stars!]