Looking at their API docs, why would you use this instead of PhoneGap?

For instance, with PhoneGap, I can easily add native Objective-C or Java classes to my project to do things you just can't do with a native UIWebView.

I solved some really interesting enterprise-y integration problems on PhoneGap by writing some Objective-C. Looks like forge makes you modify the authentication server to return a forge://url which is nice, but could be tough to get some IT environments to do. (http://docs.trigger.io/en/v1.2/features/modal.html#external-...)

I do see that you can build browser extensions, which is a nice feature.