There is a significant (and by significant, I mean Grand Canyon sized) change in writing and presentation between Episode 2 and Episode 3 (generally regarded as when Fuller left the show). I didn't much like the pilots, but Episode 3 was markedly better, and 4 just builds on 3.
Fuller left the series in October 2016 and filming didn't start until January 2017. He was already 3 months gone when the pilot started filming. Also, he wrote out the story framework for the entire first season (and, perhaps, beyond), which the current show runners have acknowledged that they're sticking to. His name is still in the credits as executive producer and, for this season, at least, it still seems to be considered his show.
The writing and presentation are exactly the same between Episodes 2 and 3, IMO, which is what you'd expect since there wasn't any staff changeover between them, after all. Many of the complaints from the pilots are still there, such as plot inconsistencies, unlikable characters, overstuffed visuals and dramatic moments that fall flat. It's just that the plot was moved forward, which it was going to do, anyway. It's not like Fuller had the whole season taking place on the Shenzhou and they completely scrapped and re-wrote the majority of the season in only 3 months. The Shenzhou being destroyed in the pilots and Burnham moving on to the Discovery was going to happen anyway. That's why Fuller named the show Discovery months before he left.
This isn't to say that there's anything wrong with believing Episodes 3 and 4 to be better than the pilots. It's just not because of changes to the show. It's almost certainly because pilots tend to be a mess (due to the conflicting goals of entertainment and establishment of characters and story) and Discovery's pilots were essentially a prologue.