I love this so much. I love how the chapter begins as if we've changed manga completely. I can imagine this was even better to read in Weekly Shounen Jump, as it really feels like Dr. Slump has been restarted, with no hint of it being Dragon Ball until Goku and Blue show up.
Growing up, I had no idea who all these characters were and these chapters were just weird. But now, coming back as a big fan of Dr. Slump this is such a treat to read. I love how we get to see pretty much every major character and of course some of them being so happy to be back that they break the fourth wall.
I also like the clash of tones we get. If the Dragon Ball and Dr. Slump crossover happened in previous arcs, when Dragon Ball was even more focused on comedy and gags, it wouldn't be as effective. And of course, the crossover couldn't fit much later, as Dragon Ball would continue to evolve and get further away from the tone of Dr. Slump. It's also fun how the crossover happens now of all times, in the middle of a struggle with a major villain, which in most manga would be treated a lot more serious. But this isn't most manga, this is Dragon Ball and I love it.