React was a very contentious decision among the Meteor community. We started off with Blazejs, which itself was based off of Handlebars. We liked the HTML-like syntax of Blaze and how nurses, doctors, and other clinicians could become familiar with it. However, the code wasn't very reusable and it was neither modular nor composeable nor testable, and became a major headache to maintain. React solves the problems of composeability and reusability and testing isolation, at the price of having worked the problem backwards and having wound up with a quirky syntax that runs within Javascript that looks similar to HTML but isn't. Nonetheless, React is quickly become a classic example of functional programming techniques, what with its' pure components. All in all, an enjoyable technology to work with that brings some sanity to front-end user interfaces.