"So it is basically a total reconstruction? Is anything real?"
Define "real". Pretty much what you see in any substantial city in Germany today, with a few notable exceptions, is largely a rebuild. Each city chose to rebuild with different priorities. Dresden made the decision to rebuild most of the city to meet the practical purposes of the post war, but they also wanted to recover some of the lost glory of the capital of the former Kingdom of Saxony.
I was there two weeks ago. The restored Altstadt is fairly small, and it's an on-going project to recreate this district block by block. It's not all completely rebuilding everything from scratch, though. Except for the Frauenkirch, the outer shell of most of the major buildings (like the Residenz Schloss, Zwinger, opera) remained standing, so these aren't just de novo recreations. Rather, consider it an massive repair job. And plenty of the extensive art and artifact collections of the kings of Saxony (the reason they called it a "museum city") remain undamaged and unplundered. I saw a significant area of the city north of the river that looks like it dates from before the war, but this isn't necessarily something that you would travel all the way to Dresden to explore. The rest of the city shows the result of postwar central planning. Clean and well kept, but rather sterile and even a bit sinister.