I have been working in the IT field for the last 4+ years and now I got a Niederlassungserlaubnis.
The Niederlassungserlaubnis means you may settle (that's what Niederlassung means) in Germany. You don't have to deal with the Ausländerbehörde any more, but are expected to do as the Germans do.
The only permission you could get on top of that is having the Erlaubnis zum Daueraufenthalt-EU, which also gives you rights in other EU countries.
You no longer need to inform your foreigners' office about job changes. If you lose your job and claim unemployment benefits, you’ll have to go to the Amt für Arbeit in your city and be subject to their requirements, but no different from how it is for citizens. Like everyone else, including German citizens, you will need to register with the city when you move, either within the same city or to a new city.
You do need to watch the expiration date on your home country passport and renew it a few months in advance and then schedule an appointment with the foreigners’ office in whatever city you’re registered in to get an updated Niederlassungserlaubnis card with a current photo and your new passport details (expiration date, passport number). Not going to be fun trying to get back in with a residence permit whose passport details don’t match your current passport...
