As any live Holdem player will know, there are always some players who like to talk more than others at the tables, and although I personally do not converse a great deal, I enjoy the social atmosphere that a game of poker creates.
At my local game there is always banter going on, and for me it adds to the enjoyment of the game. Part of the whole poker playing experience is the enjoyment gained from having a laugh with your fellow competitors, although this tends to be less the case with major tournaments.
Talking at the tables is not always is not just a way to enjoy the evening however, as it can also be useful for gathering information about your opponents. Opponents revealing what they had after a hand has finished, happens sometimes, and you should take a mental note of this to help you in a later hand. Even two players discussing the tactical rights and wrongs of the way a hand was played can offer it’s own insight into those players, and how they are likely to play hands.
In terms of the rules on talking at the tables, it is entirely within the rules of the game to discuss things in a civil manner at the poker tables. The only exception to this rule, is talking about the hand you had whilst other players are still contesting that particular pot. This is because it could give players extra information about how likely they are to make certain hands.