I like this airport, but I don't love it: more of a 3.5 stars. Pragmatism, which shouldn't be…read moresurprising, is more of the theme for this airport. This won't win any awards of its looks. However, it is pretty efficient and most of the staff are polite and helpful, unlike another German airport I know (*cough* *Frankfurt* *cough*).
Arriving here, I did not get a ton of instruction, but I managed to figure it out to get to passport control. One guy did help out in saying that non-EU passport holders had to pre-register before going into the passport control line.
I might have been blessed that day, but wait times for security and passport control flying out was not bad at all and staff was very informative and friendly.
Keep in mind that looking for various services can be a bit confusing, due to the vastness of the airport. Getting a tax refund for VAT can be a bit of a mystery. So if whatever item you're getting a refund for is in checked-in luggage, you have to go to the customs office before security to get the stamp before. However, if your item item is in carry-on, you have to go through security and passport control first, then go to a customs office post-security to get the stamp before going to whatever company you have to go to (probably either Global Blue or Planet) to recover your refund.
Another thing that was kind of annoying is that a lot of the international flights are in the satellite terminal, which isn't necessarily bad. However, the part of the terminal that my flight was taking off of only had very few shopping and dining options and we were not allowed to go to the other part of the satellite terminal without having to go through security and passport control again, even though this is a satellite terminal that is entirely separated from the rest of the airport (you have to take a train to get there). That did not really make sense. However, there are more dining options in the first part of Terminal 2, so you could chill there before you take the 1-minute tram over.
Overall, the airport was fine and, if you invest enough time, it should not be an extremely stressful experience. I would rather connect here than Frankfurt.