I think 3E is easy to customize in some ways, but not in others.
On the one hand, I now have a mechanism for making a giant insect illusionist: just take the stats for a thri-keen and slap a few levels of illusionist onto it. I can make it an infernal critter if Iwant.
On the other hand, now that I have this mechanism, I feel compelled to use it. In 2E, I didn't really have a mechanism to do this - so I faked it. I'd just grab the stats for a tri-keen, grab the stats for an illusionist, and smush the two together. If I wanted it to be a fiendish giant insect illusionist, I'd come up with some cool devilish power and slap them on top of my creation.
And it took me less time to do it in 2E than in 3E, because there was no "right" way to do it, and so I didn't feel obligated to look through the rules for the correct way to do it.
Next session, I plan to run a fairly complicated scene with some fairly complicated characters in it. I wasn't sufficiently prepared to run this scene last session, so I added in some off-the-cuff scenes that built another story arc.
These off-the-cuff scenes were non-combat. Generally, I find non-combat scenes easier to adjudicate now: the social skills, even if I don't call for rolls, give me a nice framework in which to judge NPC reactions and PC observations.
3E requires a lot of prepwork to handle combat scenes, in my experience, but not nearly as much to handle noncombat scenes. Interestingly, I find that some of my best scenes are therefore noncombat: because I'm more comfortable improvising in such scenes, I'm more responsive to my players' actions, and I can devote more attention to cool spectacles and events instead of to resolving the amount of cover (or is it concealment?) granted to the character crouching at the base of a cliff behind a scrubby tree.
Daniel