generally you need teamspeak/vent/mumble for chat since people usually don't bother using the in-game voip, exceptions being source games, Skype has also become really popular recently.
the whole "it's more expensive if you want to keep up with the new games over and over to the max details." is such a untrue and stupid rumor, i haven't played a game i cannot completely max out with atleast 4x AA, my system is 2 going on 3 years old now with a ati 5850, amd 955 BE and 8 gigs of ram, the whole thing cost me 1300$ including a 200$ case and i bought it when the 5850 came out so now you could probably shave a good 300$ off my build on that alone, so while yes it is more expensive then a console you are also far less limited and will have a better looking game that is more playable, the only game i could say thats really pushed my system is metro 2033 with tesselation on i have to turn AA down to 2x.
the pro's would be modding, usually a smaller but extremely dedicated community, dedicated servers, larger matches and lobbies, custom games, and clans matches are much more open, you can expect games to still be played 8 years from now where on a console the publishers would probably have shut the service down, example being Star Wars: Battlefront II which i have been playing a lot recently still usually has 1 full server at all times and primetime US you will find 3-7 servers with 30+ people on each of them, and of course mouse and keyboard.
for cons i would have to say lack of dev support especially on console focused games like call of duty.
