Some stuff are not found, like filter()

Well, you should have in mind that both Ionic 2 and Angular 2 are still in beta and there are breaking changes in almost every new release. As @rapropos mentioned, the Angular team changed angular2 to @angular for all Angular 2 packages with the release of RC1. That’s why I would recommend you to check out the changelog every time when you update to a newer version (because all breaking changes are listed there) - when one knows what has changed and how to update it, it usually takes 10-30 minutes to get a project up-to-date with the latest version of the framework.