Kiora’s +1 seems best at home in a Temur (Red/Blue/Green) deck, letting you untap mana dorks like Rattleclaw Mystic or Shaman of the Forgotten Ways. You then get to untap a land as well. This is pretty decent ramp but it would be even better if Sylvan Caryatid were still to be in standard.
Her -2 is a better version of Satyr Wayfinder. Like the Wayfinder you get to look at the top 4 cards of your deck and pick a land from among them and discard the rest. But with this ability you get to choose a creature instead if you wish. If there's a land there, as well, you get to take one of each. This is an ability that works extremely well with Sultai decks that want to fuel their graveyards for delve cards. But it's pretty good card filtering regardless. Getting at least 2 activations of this ability is well worth 4 mana.
The ultimate is -8 and it gives you an emblem that gives you the ability every time you have a creature enter play to fight another target creature. In addition to that emblem, you get to put 24 power onto the board with 3 8/8 Octopuses. This means you get to have those 3 tokens fight things when they enter.
For Commander, she does pass the Doubling Season test, getting the 8 counters as soon as you play her to activate her ultimate. That ultimate is amazing in Commander especially as it's any creature that enters and token creation and clone effects are rampant in the format. This allows you to essentially machine gun down entire board positions, and 3 8/8 bodies are definitely relevant, as well. If you think her ultimate will be overwhelming in standard it's many times more breakable in commander as there are plenty of ways - especially in blue and green - to copy those Octopus tokens. The other abilities have their uses as well, especially the plus ability.
While getting to her ultimate in standard is probably yet another case of Magical Christmas Land the other two abilities make the Master of the Depths playable I've already seen Hangarback Walker mentioned as a good candidate to untap with Kiora, so he can gain a +1/+1 counter and then be untapped. The Walker works in so many decks that this is a possibility. Most of the time you'll just take the free mana and untap your best creature whether it has a tap ability or not.
The first Kiora had her fans but this one seems better. Outside of Temur Midrange and Sultai Delve/Control though it's not quite yet clear where she will end up in standard.