So far, he seems to be a "high risk, high reward" character, with the majority of his moves having noticeable startup lag, ending lag or both!
His Buster Sword (alternate costume makes him use a different sword: the Fusion Sword) has a TON of range. Slightly less than Shulk (even less for smashes), but more than Ike. That makes his gameplay revolve around spacing properly his moves, although there are exceptions, such as the first hit of his down smash, which is very short compared to other moves using the sword.
Cloud, much like most Smash 4 newcomers, has his own gimmick that truly sets him apart from the cast: his Limit Gauge. This unique gimmick, most likely a down special, allows him access to Limit Breaks when fully charged.
A Limit Break is exactly what it sounds like; it breaks Cloud's limits. I noticed an almost complete lack of startup lag in the Limit Breaks we saw and some get different properties; Blade Beam becomes a multi-hit, Climhazard's recovery goes from decent to excellent, etc. They also get much, much stronger! In other words, they'd be OP if it weren't for the Limit Gauge...
Any of his Limits Breaks, which seem to be only specials (Limit Gauge likely becomes Finishing Touch when fully charged), can only be used once before having to fully charge the gauge again, making his Limit Gauge both a manual version of Little Mac's Power Meter and a more versatile one, since he would have 4 Limit Breaks.