I rode from Prague to Warsaw through Germany via Brojce in Poland all freeway except for the Czech side where I think they are rebuilding the whole freeway system, long diversions onto secondary roads and roadworks. No signs when crossing the border the only indication that I was in Germany was the road surface turned to very smooth concrete, went past Dresden and turned east just before Berlin crossing the border into Poland at Frankfurt on der Oder. This border crossing is a trap, there are signs that say cars to the left and trucks to the right, so I went left along with some cars and you see a line of cars and the Immigration booths and as I got closer I realised the cars were just parked there and the booths were empty so turned around and followed the trucks on a road that goes around this area. You do not have to stop at this border just follow the trucks and go right. Those signs should be covered up or replaced.
Poland does not have Vignettes, they have tolls sometimes you take a ticket and pay a toll at the end of the section or when you exit the freeway and sometimes they have regular toll collection points on the freeway. The total toll from the border to Warsaw was 68 zloty or 16 euro, no discounts for motorcycles. I stopped at Brojce for the night and continued on the following day, good quality freeway all the way to Warsaw.
Warsaw big modern city with a population of 1.7 million, it was flattened by the Germans during WWII and has been completely rebuilt so no old buildings. The old town has been replicated quite well and is classified as a world heritage site by UNESCO. Lots of tourists but not crowded, things are more spread out here and the roads are wider. One metro line, trams and buses get you just about everywhere for less than 1 euro a ride.