I've had my 27" 1080p Planar for the past 3 or so years, and I love it. People may complain about the pixel density on them, but I don't see how people get so caught up about it. The PPI difference between a 24" and a 27" screen isn't as bad as people make it out to be (coming from the countless posts that I've read online).
The majority of the time, I sit 3+ feet away from the monitor, and I love it. The large screen is easy on the eyes (less strain, and I don't have to sit as close to get the distance:pixel quality ratio), it's more immersive when gaming, and I'm a bit more accurate on a larger screen because it's easier to see stuff. It's just a more relaxing screen to use, be it for gaming, watching movies, or just doing general stuff.
I've seen an iMac 27" 2560x1440 screen, and it's a really nice screen. You have more screen real-estate, and you get more accurate colors with the IPS panel. The downside is that I found it a bit hard to view text on some websites, forcing me to sit closer to the screen.
For my uses, I don't need a screen like that. Most of the time I watch videos and stuff, and having a 1200p+ screen won't do anything with content that's encoded to 1080/720. So, I just stick with 1080. A higher res screen may look sharper, but it's really dependent on what distance you sit from the monitor.
Check out the attached excel document. It calculates the optimal viewing distance depending on what size tv/monitor you have, eyevision, and the resolution of the tv.
24" 1080p: 37.5in away for ideal visual acuity
27" 1080p: 42.1in away for ideal visual acuity
27: 1440p: 31.6in away for ideal visual acuity
Now, those numbers aren't final (I got them by punching in the resolution/size in the attached excel document), but my eyes agree with the distances, and it serves as a good reference for comparing the preferred distances for different monitor sizes and resolutions.
The monitor I had before my 27" was a 20" 1600x900 monitor. It has the same pixel density as a 24" 1080p monitor. I'll never go back to a smaller screen. I had them side by side before I boxed up the 20", and the difference isn't as hyped up as it is on the web. Yeah, the 20" looked sharper, when my eyes were like 1ft. from the screen, but in general usage, the 27" is better in every aspect. There's a reason why people with larger monitors can't (or find it very hard to) go back to a smaller sized monitor. Reading reviews and impressions on the internet is one thing, but experiencing it for yourself it a whole different story.
theater_calculator_v4.0.xls 100k .xls file
Edited by airisom2 - 11/14/13 at 7:01pm