I think it's way ahead of the PS3 and PS4 OS. PS3 had a terrible store, the in game XMB was largely pointless. So many things you could click on during game but couldn't actually do during game. Way too much screen real estate for pictures, movies, video, web browsing. The vertical game list wasn't as nice as the tile approach there is now.
PS4 was also disjointed. The tap of the PS button offering features got better over time but it wasn't always like that. But the tap of the PS button never makes you feel like you're far away from your game. There's so much you can do without pulling away from a game.
The integrated store is nice, too as well as the quick share features. And the shareplay function is light years ahead.
With the new update bringing vertical trophies, I think the most important thing left is just folders and other organizational tools. It'll come.