I have been using Skype for several years and as most of my business is done online I spend about 10 hours a day on Skype. I have seen the quality of service decline since it was first discussed that M$ were going to buy it. The guys that ran it before obviously lost interest the moment that the deal was discussed. Microsoft took over and it continued to suffer and I was shocked to hear that they were dropping MSN as they really did seem to be running down Skype.
I know the alternatives and many colleagues will say "lets move to Oovoo as it always works better" , some still use Yahoo messenger as it is better in low bandwidth countries (if you are going to the Philippines, get a Yahoo account) or some other provider like QQ (China). I try to encourage my hard core colleagues to use RetroShare as it is more secure (only 4 do) BUT the reality is that more than 95% of the people that I work with, who are all computer literate, want to stay with Skype because it is what they know and are happy with.
I cannot explain why because I hate Skype, it is rubbish. Its main feature is that it is easy to install. If you want to video chat with more than one colleague Oovoo will do that for free, if you want security you must use RetroShare.... but for talking to your granny, I suppose you have to use Skype because it is the only one that she will get running on her PC. Non geeks will never master RetroShare but as you are a geek, I really recommend you try it.