[maxpert]

Have recently moved system from TS + Angular 1 to Angular 1.5 and then to Angular 2 (took us solid 1 year and you can still see some traces of older code), by time we finished move to 2, Angular 4 was released! And now this! This is WTF moment of my life.

[ptmcc]

There's very few incompatibilities from the 2.0 release onward.

A few minor things here and there, and a few deprecations, but by and large most everything that worked in 2.0 should still work in 5.0.

[romanovcode]

Should be pretty easy to migrate from ng2 to ng5.

[baristaGeek]

HttpClientModule is probably one of the most visible incompatibilities, and it's one that is worth the migration process.

[jmkni]

Moving from Angular 2 to 5 is like moving from AngularJS 1.2 to 1.5.