To give you an impression of things that might speak against using Skype (not that I want to imply that these should matter to you. I merely want to speak for the 'I'd like to leave (but cannot)' side):
1) It's proprietary. We cannot validate the protocol without reverse engineering (and even then they'd be free to break/change it). The security of Skype calls, one of the loudest arguments for using it, is dubious and it seems to be a fact by now that governments are allowed to/capable of recoding your calls.
2) Resource heavy: If you ever compared a Skype conference (audio only) with any other system, the resource usage is ridiculous. Mostly CPU, but also network wise.
3) In your face advertisements: The (unacceptable) UI constantly pops up with 'subscribe here'/'buy credits there'/'did you know all the other ways you can hand over your money'. You can turn off most of these, but an update usually leads to the very same thing.
4) Maybe related to the P2P architecture: The behavior is unpredictable at times. I often see people online, they don't see me. Or vice versa. I can talk to someone on Skype, but messages (say, a link) fail to be delivered. Sometimes messages queue up for hours and completely lose their meaning when they arrive at 1am, asking about having lunch.