Another problem I've seen is that the default data binding being taught to new comers is slow. At least slow enough for a team I was on to later have switched to an approach where you must manually tell the UI when to update with calls to detectChanges() all over the place. The way to avoid that is to fully embrace Reactice Extensions, but that seems to be very hard to grasp for a lot of developers that instead work around the library in all sorts of quirky ways (subscription()'s everywhere, that you must remember to dispose, that calls detectChanges()....).