Memory and crashing issues with Safari on iOS 9
It seems that Apple has introduced some memory management feature with Safari in iOS 9 that causes large templates to crash Safari during parsing. Fortunately, this can be worked around by splitting your templates into smaller partials or, more efficiently, by pre-parsing your templates and serving them as a JS object. You can use ractive.parse() to create the JS object as a build step or when the page is being served.
Since there isn't really any browser for iOS other than Safari, all browser on iOS 9 are affected by this issue. iOS 8 seems to remain unaffected.
Using Ractive with...
Building an app with Ractive
Ractive can take care of your UI, and for simple applications it can take care of your application state as well. But if you're building a complex app you'll likely have other things to worry about as well - routing and history management, fetching and saving data to and from a server, validating data, handling realtime communication, user authentication, and all the other fun stuff that goes into a web app.
Unlike mega-frameworks like Angular and Ember, Ractive doesn't have an opinion about these things - you're encouraged to build your app from loosely coupled modules. It means you're not beholden to a particular framework's way of doing things, and you can swap out (for example) your routing library for something better later on, but it does mean that you're now responsible for making those decisions.