Much as I like spending half a fight behind cover waiting for either my shield's recharge function or the enemy to share the fire and missles with the rest of my squad, melee shepard might be pretty damn fun, if you'll excuse my partially biased I-like-punching-things standpoint.
EDIT: (Since it's in half the thread now, I won't bother spoiler-ing this) I recall that renegade/saved-the-collector-base Shepard said something like "If you get greedy or delusional with power, we're all screwed." in the last conversation between him and Illusive Man. Shepard sounded angry even though I'd been trying to get along with Cerberus that whole playthrough. I don't really get the impression our choices have a lot to say in the long run, even though I saved the Rachni, I probably won't get more than a few bugs that would have been there anyway turning to help me in a few encounters. If that's the case, what might be the point of someone going back to play the first two when 3 is out?