Facebook ironically does not build real native apps, they are just beautiful HTML wrappers. FB apps are an example of user experience regressions, as they were by far snappier two years ago.
Of course, if even Facebook prefers to build HTML apps what are the odds that smaller companies are going to go to the extra trouble and expense of native?
Pseudo-native HTML apps are inferior, and people will notice it. I'm quite fed up with the FB apps on both iOS and Android because they spend more time with loading than the in-browser version. It's so bad that I actually considered if FB wants to drive people away from mobile so they click more ads in the browser - I don't think that's really the case though.