Whenever Dragonlord Ojutai deals combat damage to a player, you get to look at the top three cards of your deck. You get to choose one of them to add to your hand and the other two go to the bottom. It's useful card filtering and you'll want to be swinging quite a bit with Ojutai anyway. (Interestingly enough, this ability is actually the same effect as another card printed in Dragons of Tarkir called Anticipate.)
While this card doesn't look too exciting for Commander, it's not bad at all. It's certainly playable in Standard as an aggressive curve-topper that provides quality card advantage. Really, she's playable in Commander too as a complementary piece, as card advantage is just as important, if not more so, in a singleton format.
Ojutai, Soul of Winter did have the decent ability to be able to tap down a nonland permanent for each Dragon that you would have attack. While said permanents wouldn't untap during the next turn, that wasn't enough on a 7-mana creature, even one that was a 5/6 flyer with vigilance. The Dragonlord trades the vigilance for the partial hexproof, and the card advantage beats the very conditional tap trigger. Neither is too great to build around, but the Dragonlord version is clearly stronger overall. Ojutai definitely is good.