Speaking from a GM's perspective, what I see as interesting in 4E are actually not individual powers, classes, characters or whatever, but how they combine and mix to form "more than the sum of the parts".
As an example, here is a sequence from the game I GM:
- Fighter wades into the thick of the fight and triggers Come and Get It - gathers foes around him and strikes at them all.
- Rogue moves into a flanking position on one of the 'corner' enemies and shoots it, triggering an opportunity attack, which the fighter punishes with an interrupt (Combat Challenge) before the Rogue strikes with sneak attack and flanking.
- Warlock uses Fey Switch to swap places with the Fighter amid the swarm of enemies - and then uses Otherwind Stride to leave in a flash of explosion, damaging the gathered foes again. Oh, and immobilising them.
- The enemies now being neatly gathered in a 3x3 square with none of the party within it, the Wizard hits them with an Area attack that leaves a nasty zone behind, and
- Finally the Dragonborn Paladin breathes on them before attacking and shifting away.