The Cumulus is ASICS' plain daily trainer, and that is meant as a compliment. FF BLAST PLUS foam with PureGEL under the heel and a FLUIDRIDE outsole gives you a smooth, unremarkable ride that gets out of the way, and at 265 g it is light enough not to feel like a chore.
It suits runners building a first proper mileage habit, and anyone who wants a shoe that simply works for easy and steady runs.
It is not exciting. There is no plate, no real bounce, and it will not make you faster. It is also not enough shoe for marathon-length runs on hard pavement if you like a lot of protection - a Nimbus does that job better. Buy it as the pair you stop thinking about.