New monitors based on TN panels are becoming increasingly rare. Only their faster response times make them useful for gaming. For all other purposes, IPS and PLS are the better choice, and they're the dominant technologies in LCD flat panel manufacturing as a result. Besides improved contrast and color accuracy, superior off-axis viewing performance is a hallmark feature.
The P2714T looks similar to other IPS screens we’ve photographed. Light falloff is minimal to the sides and a little more pronounced in the vertical plane. While there is almost no color shift from bottom to top, a slight blue tint appears when you reach a 45-degree position to either the left or right. Detail in the dark end of the brightness is retained pretty well. You can still see a difference between the zero and 10 percent bars.
Screen Uniformity: Luminance
To measure screen uniformity, zero- and 100-percent full-field patterns are used, and nine points are sampled. In a change from previous reviews, we’re now comparing the results to other monitors we’ve measured. First, we establish a baseline measurement at the center of each screen. Then the surrounding eight points are measured and their values expressed as a percentage of the baseline, either above or below. This number gets averaged. It is important to remember that we only test the review sample each vendor submits. Other examples of the same monitor can measure differently in this metric.
First up is black field uniformity.

Given some of the past results we’ve recorded, this number is a little surprising. While 14 percent isn’t poor performance by any means, there are plenty of monitors that fare better. On our review sample, we could see slight hotspots on the left side and center of the screen.
Here’s the white field measurement.

In the white field measurement, we see that the center of the screen is ever so slightly brighter than the surrounding area. You can barely tell though, and again, we're splitting hairs.
Screen Uniformity: Color
To measure color uniformity, we display an 80-percent white field and measure the Delta E error of the same nine points on the screen. Then we subtract the lowest value from the highest to arrive at the result. A smaller number means a display is more uniform. Any value below three means that variation is invisible to the naked eye.

The P2714T’s color is the weakest in our uniformity measurements, and we can see slight variations in a vertical band pattern. One band is slightly blue, while another is slightly green. The all-important center area of the screen is the most accurate. It’s possible (if not probable) that the panel's touch layer plays an influential role in these benchmarks.
- Dell P2714T: A 27-Inch IPS-Based Touchscreen Monitor
- Packaging, Physical Layout, And Accessories
- OSD Setup And Calibration Of The Dell P2714T
- Measurement And Calibration Methodology: How We Test
- Results: Brightness And Contrast
- Results: Grayscale Tracking And Gamma Response
- Results: Color Gamut And Performance
- Results: Viewing Angle And Uniformity
- Results: Pixel Response And Input Lag
- Touch Or Not, Dell's P2714T Is A Solid Performer

I said it's a crappy idea that's not going to catch on, and I'd prefer not to have to pay extra for it or sacrifice other aspects of the display, like resolution in this case. That said, the companies can put their R&D and marketing $ wherever they want, not my money, but it's still dumb.
So instead of injuring your arms from repetitive stress holding them up in front to touch the screen, you are going to get RSI, cramps or other problems in your neck for staring at a steeper down-angle for too many hours a day... or get both problems, albeit over a longer term than either extreme, if you put the touch-screen somewhere in-between.
This is going to be 'fun' 10-20 years down the road. (As in lawsuits due to not being warned by device manufacturers that extended use of their device in a typical setup may lead to injuries.)
On the plus side, as long as it is only the glass cover getting dirty, it is much easier to clean than a keyboard or mouse.
Kiosks is a nice use of touch since it is pretty easy to "secure" those by simply omitting unwanted access in the UI design with the rest of the system physically locked out - touch-based kiosks have been around for a long time: the first time I have seen a touch-based terminal was in a video rental store about 15 years ago and the menu was in good old 80x25 text mode.
Industrial touch applications are nice too since you can seal the display on the "dirty" hot side of the application and lock the rest on the "clean" cooled weatherproof side.
For everyday computing, touch may also have its uses such as when demonstrating stuff: instead of demonstrating software or page layouts by pointing things out on the screen with fingers and then using a keyboard/mouse to activate the object or navigate pages, clickable things can be demonstrated on-screen - you already have your fingers in there to point things out anyway.