They seem optimally designed to ensure that you'll have glare on your screen no matter how you position it in any kind of well lit environment.

At work we have dozens of curved monitors by Dell. Not once have I seen glare on them.

They don't offer the window management affordances that having separate screens do, or they have some weird software kludges to do similar.

But once you have figured out the window management stuff, they do offer better ergonomics! (And you don't have to daisy-chain monitors, etc.)