EU4 starts “in media res” while Stellaris has a typical space 4x start and is meant to transition to an EU4 state once things start to get filled in. To me at least, the process of exploration and initial colonization is interesting enough, especially with the archaeology, expanded events and new origins.
Generally I find it’s once the EU4 part starts that I start to lose interest. I have to admit though that my current game is pretty engaging so far. I think the changes have had a fairly positive reception on the Paradox forums as well.