Impressions from the demo:
Mario seems... Better. I've always liked using Mario, and he seems more solid, his smashes seem a bit stronger, and his Down B is actually viable now, because it lasts longer, is more powerful, and takes a short time to charge. Not meaning I'll ever really use it though.
Link is for sure the best character on this roster. I've always liked using Link too, and he's faster, more powerful, and just overall better. Way better. Not to mention his ARROWS can KO when fully charged in Sudden Death. Then again.. Just about everything KOs in Sudden Death.
Pikachu seems nerfed to me. Maybe Pikachu is the new Fox. Fox was one of the best if not the best in Melee, and got Nerfed to be faster with less power. Seems Pikachu got the same treatment from Brawl to SSB4. That being said, I like Pikachu's new Down B as a spike. Very handy at times, though a bit risky with that ultra annoying Up B recovery I hate. Overall, Pikachu got a downgrade, but seems a bit faster for it. A harassment character? Maybe.
Megaman seems to be the weakest character here at first, but when you actually play him the way he's supposed to be played, he does well. His side smashes are above average to me, and they have good reach. His A combo is very nice; It works like Peach's A slap in Brawl, which was just a nice combo breaker at 2 frames (fastest of all moves in Brawl). Mega Man's bullet spam with A will rack up a bit of damage when your opponent tries some stupid frontal assault when he gets sick of your constant barrage of Leaf Shields, Saws, and Explosive Missiles. I like his Down A too, very nice surprise attack if you time it just right. Maybe Air Down spikes. I don't know yet. Air Up looked pretty nice, reminded me of Game And Watch's Up Air with blowing up opponents, except way less accurate.
Villager? The ultimate Troll God. For sure. I can't play him well, because that's not generally my style of Smash Play, but I've seen him in action. Very nice Defensive/Troll character. And for GOD'S SAKE, DON'T UNDERESTIMATE THE TREE ATTACK!!!!!!!!!!!!! Seriously. It's a nice shield (Mega Man's Saw goes right though it, but then there's Neutral B for that
), and if your opponent approaches, CHOP CHOP. I also like how Villager doesn't have to commit to his sprout. You can use the watering can to push opponents slightly, or the Ax, though I haven't tested the Ax as a fighting move as of yet. But yeah. I hate Villager's Smashes. Side Smash is good, but it has no reach at all. Up Smash is good for racking up damage, but doesn't seem to launch well. Down Smash is nice, except any old decent player can escape from a dirt pile quickly. Overall, it might be harder to kill with Villager. I also hate his Up B Revovery, but love his Side B attack, though the delay in that attack is more than enough to counter with a Mario Cape or something. Usually, I'll charge right behind the Lloyd Rocket and attack that way. Also, Radishes. And Slingshots. His Air Game is niceish.
Those are my thoughts on the Demo as of now, from a rambling fool who barely knows anything about Smash.