As most of the posts above say, Skype surely offers a really good value for money. For the cost, a rare occurrence of lower quality is acceptable. But, what I would question is the security of skype communication. My personal skype account was hacked and someone foreign used all my credit. When I reported it to MS, they did not take any responsibility. Few days later, there was publication in the news (around Nov'12) where MS accepted skype accounts being hacked really easily. I never got any refund or apology for what happened to my account.
This, obviously, prompted me to look at alternatives. I found a few good solutions -
a. Asterisk hosted solutions
b. Hipchat
c. Big blue button (open source)
For business purpose, depending on the type of communication, I now choose the channel. For example, the internal team communication is via Hipchat which we host internally and security is paramount for us. For a presentation session with the clients, I use big blue button which is far more feature rich then skype business video/ screen sharing function.
I must accept, I still use skype because the adoptability of skype is too high and more or less everyone you want to communicate with outside our organisation has skype on the phone/mac/pc.