My take on Meta-Knight is this:
General
At this point in time, MK looks to be almost broken. He has multiple jumps, and apparently, his aerials are so quick that he loses no air time between them. He has a multi-hit lifter that doesn't look like it would be too easy to DI out of, and the lifter has little lag (it is seen in the video that MK combos it straight into his multi-hit aerial). So, on the offense, he is deadly, comparative to SSBM Fox.
It looks as if his cloak can be used as camouflage. If this is merely an Easter Egg effect with his shield that has no other use, fine. And it seems to be that way. Nintendo, keep it that way, we don't need an assassin type character that never gets hit. Hopefully, they make don't give him too much defensive prowess, otherwise, yes, he will be broken.
Offensive Game
As mentioned above, his ability on the attack is comparative to SSBM Fox. Once he gets into you, he'll probably have a 0-death combo on nearly every character in the game. This is accentuated even more by the fact that, at this point, his aerials have almost no lag (proof is in the video, the segment with MK vs. Pit in the air. MK does his multi-hit aerial and loses next to no airtime). Unless this is changed, say "Hi!" to a Jigglypuff with a shorter-ranged Falchion, folks.
With those rapid aerials, MK will have no problem breaking through most defenses. No question about that. But what about his defense?
Defensive Game
Much is to be said about this. But, to say, one must remember that Meta-Knight is literally a blue Kirby in armor. Therefore, he would only weigh slightly more than Kirby, and fall slightly faster. So, we have, right now, a small size character with Med-Low weight and Med-Low falling speed. That would make him vulnerable to most upwards KOs, and by the looks of it, there are many more powerful usmashes (just look at Kirby's. It KO'd Mario and Link at the same time.). This would severely limit his defensive game, making MK rely on dodging and mindgames to avoid even getting hit.
As mentioned previously, MK's cloak should either be stationary, or have a really short invisibility period. He could, quite literally, stay in the shadows and strike. Ultimate mindgames, people! 'Twould be broken if it was kept this way.
Recovery
One word describes MK's recovery ability : Broken.
1.) Multiple Jumps.
2.) He apparently has the ability to glide after the jumps.
3.) His anti-lag aerials allow him to fend off edge-guarders with ease.
4.) Med-low falling speed + Multi-jump + Glide = Off-Stage camping, sort of what Jigglypuff can do.
I feel no need to continue with this, because it is obvious that his recovery may end up rivaling (and most likely surpassing) SSBM Samus, SSBM Jigglypuff, Peach, and SSB Pikachu.
Speed
Fast. Really. Fast. At least, in the air. Not much of MK's ground game has been revealed, but I would assume that it consists mainly of high speed sword attacks. Okay, he'll never be as fast as SSBM CF or SSBM Fox, but no character in SSBB ever will. At least, that's what I think.
Final Verdict
MK, for now, seems to be very much Top-Tier material. His Offensive and Recovery games are both nearly broken, with only his defense somewhat lacking. Nintendo would have to make his defense Medium at best, just to keep him balanced. Sure, he lacks projectiles, but so does Marth, and that didn't keep him off Top Tier/High Tier. Suggestions?
1.) Make him light. Really, really light.
2.) Make him a fast faller. That way we won't have a Jedi-puff.
3.) Give him a slow roll and spot-dodge.
4.) Make the glide duration short.
At this, I end my post.
~ Crusader