On the surface, the £299 Dell S2740L - an LED-backlit, 27-inch display with a high-quality in-plane switching (IPS) LCD panel - looks like a great deal. See also: Group test: What's the best flat-panel display?
Dig deeper, though, and the reason for its attractive price becomes apparent. Yes, the Dell S2740L does use high-quality components, but the resolution is considerably lower than that of Dell's own U2713HM or of Apple's LED Cinema Display review.
It comes down to pixel pitch. For a 24-inch display, 1920 by 1080 pixels is not a low resolution, but when you spread those pixels out over a 27-inch display such as the Dell S2740L, on-screen elements appear much larger than they do on a 27-inch display with a 2560-by-1440-pixel resolution, such as the aforementioned U2713HM and LED Cinema Display. In some instances—or I should say, at some distances—larger elements can be beneficial.
Presentations and games look better when you're sitting a few feet or more from the screen. When I sat directly in front of the Dell S2740L, as one does in a traditional desktop-computer setup, my first instinct was to back up. The individual pixels are visible, which can make text look a little jaggy. In many ways, it's the opposite of a Retina display.
The trade-offs don't end with the resolution, though. While the Dell S2740L offers VGA, DVI, and HDMI connection options, only an inexpensive VGA cable ships with the display. To use this monitor with a Mac, you'll need to buy the appropriate adapter, depending on the video output connector on your Mac.
The Dell S2740L's stand is limited to a few degrees of tilt, while the more expensive U2713HM offers height adjustment and the ability to pivot the screen into portrait mode. And even though it's just a one-time issue, I have to note that the S2740L ships in a box full of styrofoam and that its stand needs assembly before you attach it to the monitor.
I should also point out that the Dell S2740L has a glossy screen. I don't mind glossy screens, but you do need to take that into account when you're deciding where to place the monitor. Glossy screens can help photographic images appear to have more depth, but glare can be an issue. The display did well in our on-screen tests, showing smooth gradients, a very good viewing angle, and pretty good text.