Some info about e-IPS panels...
The majority of e-IPS panels are 6-bit panels which are similar to TN panels. This is done to reduce costs, but the side effect is less color accuracy since 6-bit panels can only produce 256k actual colors. Through a process generally called temporal dithering, around 16m colors can be "blended up"; 8-bit panels can produce 16.7m actual colors. for most people 6-bit panels are fine, but anyone who requires color accuracy should look at 8-bit panels (VA and other IPS panels). 6-bit panels tends to have color banding issues when there are fine color gradients. Some general image artificats might appear here and there, but you'll only notice if you know what to look for. I think these issues are less noticable on an e-IPS panel though.
Last time I've checked, there are only 2 e-IPS panel models that are actually 8-bit panels. The older NEC EA231WMi supposedly has an 8-bit e-IPS panel. When compared side by side against the Dell U2311h which is confirmed to have a 6-bit e-IPS panel, the NEC EA231WMi seemed to have few color banding issues and color distortions. All e-IPS panels that have LED backlight are 6-bit panels (including the NEC EA232WMi) based on the latest panel specs released by LG Display who is the only e-IPS panel manufacturer.
The 1st generation e-IPS panel all basically had 8ms response times; decent for general usage an casual gaming, but most hardcore gamers prefer 2ms or 5ms response time TN panel monitors. Some of the current 2nd generation e-IPS seem to have 6ms response times which is inline with the more expensive H-IPS / S-IPS / P-IPS panels. 6ms is definitely good for gaming because I play games on my NEC LCD2690WUXi monitor which uses a H-IPS panel. My Planar PX2611w (H-IPS panel) is rated at 5ms, but I only use that as a secondary monitor. NEC's e-IPS monitors ( NEC EA231WMi and NEC EA232WMi) tends to lack response time acceleration which explains why their response times are listed as 14ms and why they are not recommended for fast action 1st person shooters.
The e-IPS panel was designed to compete against TN panels which are inexpensive to manufacture. The distinct advantage of e-IPS over TN is the wider viewing angles which means less color shifting / fading when you move your head around. It also can provide slightly better color accuracy even though it still is a 6-bit panel. I may have even seen a few e-IPS panels monitors that were rated as fast as 5ms, but that's probably due to aggresive response time acceleration settings. The downside is e-IPS panel monitors are slightly more expensive than the average TN panel monitor and they are not as fast as 2ms TN panel monitors.
Regarding color cablibration, all monitors needs calibration especially if accurate colors are extremely important. For best results a colorimeter (hardware) is required and the really good ones can cost up to $300 (the price of some low end monitors), but they generally start at around $60. There is also the manual way of doing things, nowhere near as accurate, but it is free. Websites like Lagom can help:
http://www.lagom.nl/lcd-test/
Dell generally ships their monitors pre-calibrated, so out of the box the colors are generally good and for those people who do not require extremely acurate colors that save them money. However, in situations where color accuracy is important, then buying a colorimeter is still highly recommended.