There are actually two main React libraries for ClojureScript, Om[1] and Reagent[2]. There are also other libraries for doing the templating if you prefer hiccup[3] or enlive[4] style templates, which I find a bit more readable than straight function calls.
Overall though, React seems to be shaping up as a great solution for building reactive templates that isn't tied into larger frameworks like the solutions within AngularJS or Ember.js.
There are three ClojureScript React libraries I've seen, each with a very different approach.
Reagent is basically just a native interface to React.
Om sort of reimplements React on top of React with a few modifications to make it more ClojureScripty (e.g. taking advantage of persistent data structures for state).
Quiescent takes React and turns it into a simple rendering library, leaving out any concept of state management.
ClojureScript also has a nice react kind-of-thing (now named reagent), though all the parenthesis makes it more noisy.