I've heard plenty of gripes about Skype. I've heard analysts and bystanders say that Skype can't compete with other VoIP platforms. I've heard it's got security holes. I've heard people say it's annoying to talk from your computer. I agree that ebay paid too much for Skype.
Despite all this talk, Skype is now used for real business. As far as I can tell, it's at least as popular as fixed line.
In other words, these gripes and swipes simply aren't true. While it is true that Skype is essentially a proprietary client, and other softphones are "standard" SIP (I know enough about SIP for the idea of standard to be in quotes.), meaning they should be able to call one another, in fact this isn't of much concern to anyone. People still use regular phone numbers and for all intents and purposes, SkypeOut and SkypeIn are no different than the interfaces of any other VoIP interfaces.
For all the talk of Skype security problems, I have not heard one live actual account of a security breach due to Skype. I spoke to one of the Skype founders who told me the same thing. Not one live incident. If you know of one instance, by all means comment (and I don't mean you heard of it or read it on the Internet -- I mean, do you know an individual who had such a problem, not an IT manager who claimed it was a problem).
The bottom line, basically is that Skype has got it right. I can't put my finger on exactly what is right, but everybody has it on their desktop. Today, it's absolutely acceptable to tell a business contact to Skype you, and it's relatively rare for anyone (at least in the technology industry) to say they don't Skype.
The main convenience of Skype over other forms of communication is what people in the industry call "presence". That means I know if you are available before I, um, "dial", the, um, "device". It's also convenient that it's free, you don't really dial, and you see people's name instead of their telephone number, but those features don't change the basic functionality the way presence does.
Presence is revolutionary for two reasons. The main reason is that we no longer need to set fixed meeting times. I recently set a teleconferences with a collegues defining the time as "Some time between 4-6 pm. Look for me on Skype." We didn't have to sit by our desks, worry about stopping in the middle of the previous call, or any of that. We just "saw" one another online. Another meeting was defined by "Wednesday or Thursday afternoon next week when we are both online." Obviously, these weren't the most important meetings on my schedule, and they didn't involve more than 2 people (though Skype is amazing for that, too.), but you get the idea. Using Skype is changing our concept of scheduling. I don't know whether this is good or bad, it just is.
The other reason presence is revolutionary is that getting a phone call really never needs to be an annoyance anymore. Although sales guys have my Skype address, they don't take advantage of it any more than my regular fixed or cell number. I'm an extremely accessible person, being as I have customer-facing as well as spokesperson roles at my company. It's easy to find my cell phone phone number.
Despite my accessibility, my experience is that the best sales people are never an intrusion. With Skype, if they want to call, the usually will open a "chat" first and ask if it's a convenient time. Yes, they could have done the same thing by picking up the phone, but somehow, the quick chat is much less of a bother. Sales people who don't use Skype are starting to be much more of a bother to me than those who have access to knowlege about whether I'm online.
Given this, it makes sense that Skype would also integrate a feature that would allow me to define "work" and "real" friends, and define my status accordingly. That is, when I'm at work, my work colleagues would see me online, but they wouldn't see me online when I am at home. If it integrated with Plaxo to adopt those attributes, wow, I'd really be in heaven then.
Meanwhile, feel free to Skype anytime.