I have some experience of using the version 1 skypephone. As long as you have 3G reception then the skype calling and skype chat works pretty well. However if you don't it's pretty much useless for skype. The other interesting feature is that the phone will work as a usb modem, and you can buy daily internet, weekly internet or monthly. If I remember correctly it's 50p , £2.50 and £5 (daily, weekly etc). The downside to the v1 skypephone is the low connection rate of 115kps and the fact that you have to install drivers and getting it to work on Vista is quite troublesome. (Although it can be done using the T-Mobile web and walk s.ware!). Msn messenger is also free on this phone, and you can watch TV stations on the phone. The quality of the unit is poor though, I've already sent one back under warranty and I got back a different phone which works fine but was in a very shoddy looking condition.
The skype works via the phone carrier mobile signal and not via wi-fi, and works in any country in which 3 has a network (previously listed in this thread).
The version 2 skypephone is far more interesting because it has a modem with built in drivers and it works at up to 3.6Mb and considering the what I regard as cheap internet tariffs from free it seems a no brainer if you want mobile internet access.
Top up and get free skpye, msn etc. The credit you topped up with stays and you can use it for normal mobile calls, texting, tv etc.
If you can live with the cheap phone and don't require fast mobile internet access. (Internet access on the phone itself is reasonable fast in a 3G network) and you will use the skype feature then it's great.
Personally I much prefer the spec of the version 2 skypephone. I'm completely ignoring the camera aspect of both phones are they are both pretty rubbish for taking photos.
I must stress the fact that the main selling point of this phone Skype and to some extent free msn messenger is only of any use if the phone or phones are in a 3G area, otherwise it's quite flaky and unreliable. You can talk and skype chat from a handset to a pc and vice versa, you can't make skype in or out calls, although there are work arounds on the net. The three skypephone forum is a place to visit for more info, there is a FAQ there >
http://3skypephone.com/forum/viewtopic.php?t=665