Flatpaks are really outrageous in size...I have tried to use flatpaks for the past months but man o man....hundreds of MB for each package, takes forever to update them even on my 1GB internet connection. The idea is great, but this is such a huge downside that I cannot see how it is going to make the flatpaks easier to use than normal packaging.
Look at this for ungoogled chromium:
Had to download around 4-5 GB....insane!
@tio probably really depends on your usecase. For my slow internet connection, I really love how Flatpaks are an exception to the "partial upgrades are not supported" problem. Just because I need to install discord it does not mean that I want to do a 2,3GB update to my system, my friend is waiting for me.