Surprises me each time I see someone still uses that messenger service

a lot of my pals use it. It works with 3d party chat aggregators very nicely so you can use it on whatever computer and operating system you want. Skype isn't like that. It sucks.

Agree there. Skype's became a real memory hog under Linux, considering its doing less than what Pidgin, Telepathy or Kopete do.

I use a lot of protocols:
aim
icq
yahoo messenger
xmpp
skype
irc
mumble
googleTalk / Google's variant of xmpp

In theory even my MSN account would still be used by me if it wouldn't be down server-sided

I'm watching the datatraffic Skype produces very closely. When it starts transferring noticeable data outside that needed for communication, it's off the drive.
The main reason to stick to the old protocols is that they really can't do much harm running through an aggregator ( Pidgin, Kopete, ... ).

Skype, which needs its special program, might or might not be on a straight way to something like a trojan horse for all that I know.
So outside of work requiring a Videochat, I was always more puzzled about people still joining Skype, especially after acquisition by Microsoft.

plus it has those ads for some baffling reason. I'm not opposed to ads. But IM chats are the least necessary place to have them.

yeah. And whilst for nearly 10 years you could stick with an old client, first thing Microsoft did was making it so that it can force you to update your client, and thus I'm countign the days when even under Linux I'll have some Skype client throwing ads at me.