Angular and Ionic myths

As you go forward, you will hear many myths that are not true in respect to Angular 2 or upgrading to Angular 4. One of the most common is the Angular 4 doesn't support two-way data binding, which is not true. The Angular team has made sure that we use forms as simple as we use in Angular 4, they just have a new syntax:

      [(property-name)]="expression"

   <input type="text"    
      [(ngMmodel)]="model.name" />

We still have two-way data binding. Although, to improve the Angular digest cycle and performance by default, we don't use two-way data binding. It uses a unidirectional binding that we can extend to two-way binding when we require it. You can refer to Angular template syntax to demystify all other syntax's and their uses available with Angular 4.
Ionic lack URL navigation is another discussion going on at the Ionic forum. Again this is also partially correct; because Angular-router was not stable enough, the Ionic team decided to remove it in the initial beta version. As of now, Angular-router is stable and will be in Ionic. The Ionic team understands how critical it is to have a proper routing mechanism and to make a developer feel at home while moving towards Ionic 3.
Upgradation is entirely rewritten: Angular 2 is itself rewritten, but you don't have to rewrite your app also. Initially when I started I felt the same and thought that we had to redevelop our current application. But there are many tools and documentation (http://ionicframework.com/files/Ionic2Migration.pdf ) available for a smooth upgrade from Ionic 1 to Ionic 2 or 3. You just have to be careful as if you have a complex application then you might have to do many things manually. But one thing is for sure that upgrading the application will surely not take that much time when you build the same application from scratch if you have proper expertise and a concept of Angular 2. One of the reasons behind this is that you already have a running application where you just have to assemble the moving parts in different ways, as most of the application logic will be same.
Personally, my learning process with Ionic didn't think too much about I upgrading to a new version. Rather I took it as new improved concepts that came in new Angular versions, designed to ease the learning and understanding.