The original phone's taco-shaped design was considered clumsy: to insert a game, users had to remove the phone's plastic cover and remove the battery compartment as the game slot was next to it. Another clumsy feature was the speaker and microphone being located on the side edge of the phone. This often resulted in many to describe it as if one was talking into a "taco phone" or "Sidetalking", or simply that they had one very large ear, because the user held the edge of the phone against the cheek in order to talk into it. The comfort factor of lengthy calls was also called into question. Despite the criticism, it is thought that the speakers were there for a practical reason: if placed elsewhere, the screen would get in contact with the cheek and become smudged. However, almost all other cell phones have the screen against the cheek when the user is talking. Despite the questionable practicality, gamers were still unwilling to talk in such an awkward manner.
When considered from a video game point of view, the N-Gage was known for its unusual screen orientation, a vertical one as opposed to a horizontal one (which is more popular with other handhelds). The reason for this was that the underlying operating system, Series 60, did not support horizontal orientations at that time (only supported since S60v3 ). Some felt this to be a negative feature, feeling that 'unconventional' does not necessarily mean improvement. Possibly due to this screen feature, as well as the public's luke-warm reception to the device, the game library was far from extensive. Despite this, the N-Gage did manage to garner some well known franchises such as Tomb Raider, Sonic, Rayman, Red Faction, Tony Hawk's Pro Skater, The Elder Scrolls, among others.
Source: Wikipedia, "N-Gage", available under the CC-BY-SA License.