Switching sets was very unwieldy, since it put all your powers on cooldown, leaving you with just your guns. It didn't bother me that much when I played a combat-focused Ryder, who had a lot of powers with no cooldown and a lot of points in the weapon passives. But when I began a playthrough as a power-focused tech/biotic Ryder, it was very inconvenient.
I'm not sure what the intention was, really. Were they worried we'd spam combos and mix-and-match powers freely? If so, that was overkill, especially since combos are weaker than in ME3. Were favorite sets supposed to be on-the-spot retraining, rather than sets of powers within the same "build"? If so, then just like Belle Sorciere said, three powers are just too few for single-player. I think just giving us a power bar with eight spots on it, to be filled with whichever powers we buy, would have worked better.