I have an Ultrawide and it's amazing. I wish it were retina but I'll take it anyway because I can have far more open at once. If I'm coding a website I can have my code editor and browser open side by side with plenty of room in each app. If I'm laying out a print document in InDesign, I can have most documents I work on open at 100& with three columns of palettes on the right so I'm not constantly opening and collapsing them. After Effects and Premiere Pro timelines go on for miles with the Ultrawide monitors and there's plenty of room for opening footage bins you need for the project without sacrificing too much timeline in Premiere Pro. Having not used a retina monitor, I can't say how much of a difference the Ultrawide is compared to the 4K or 4K monitor screen real estate.
I have an Ultrawide and it's amazing. I wish it were retina but I'll take it anyway because I can have far more open at once. If I'm coding a website I can have my code editor and browser open side by side with plenty of room in each app. If I'm laying out a print document in InDesign, I can have most documents I work on open at 100& with three columns of palettes on the right so I'm not constantly opening and collapsing them. After Effects and Premiere Pro timelines go on for miles with the Ultrawide monitors and there's plenty of room for opening footage bins you need for the project without sacrificing too much timeline in Premiere Pro. Having not used a retina monitor, I can't say how much of a difference the Ultrawide is compared to the 4K or 4K monitor screen real estate.