From what I know, Gnome tends to be more of the "our way or the highway" type, similar to Apple stuff.

If you like how they do things, it's fine. But if you don't, you need to use something else, like KDE plasma (which is very customizable).

Nothing. It's just different to the 'traditional' desktop layout.

GNOME has a very different workflow from most traditional desktop environments. It takes some getting used to, and it's debatable whether it's even a good workflow on a desktop. It's a lot more keyboard-driven and single-window/activity focused, which I find works really well on a laptop but annoys me to no end on a desktop. Here's a couple videos on GNOME 3's workflow: One, Two

There's also some political reasons people dislike GNOME - GNOME version 3 was the advent of this new workflow and it replaced/killed GNOME 2 which people really really really liked. On launch GNOME 3 was very buggy, slow, and bloated, and even though it's gotten better people have trouble shaking this first impression. Even now there's valid criticisms of GNOME 3, such as its over-simplification and need to hide/remove useful things from the users, and its over-reliance on community-maintained extensions (which frequently break on GNOME version updates) to try to bring critical functionality back into the users' hands. Its "rival", KDE, has roughly the opposite approach - giving the users as many options as can fit on a settings page and giving them options for how they want their workflow to function.

If you want the original GNOME 2 experience, there's MATE. If you want GNOME 3 but in a traditional workflow style, there's Cinnamon.