For those who prefer information by video, here is a short overview of what's new in Dymola 2023x.

https://www.3ds.com/fileadmin/PRODUCTS/CATIA/DYMOLA/Videos/Dymola-2023/Dymola-2023x-HD.mp4 

If you wonder about the new splash screen: in addition to the version data it also displays a bit of information about what is going on at start-up. In particular, if your license server is slow (or down) Dymola will show that in the last line of the splash screen.