I hate Skype for the inability to use 3rd party clients.
Looks really interesting but no support for Hangouts / Gtalk is a non-starter for me.
Yeah this is going to be an issue for them moving forward since Google Hangouts doesn't use XMPP as Google Talk did. Also, Google Talk doesn't support group chat through XMPP so their still limited on incorporating this. More importantly, Google can pull the plug at any time on supporting Google Talk through XMPP as they have transitioned to Hangouts which is completely proprietary .
No iMessage, no AIM.
I use AIM and iMessage, not Facebook & Google Talk. Sadly, this isn't the app for me. :(
This is a breath of fresh air compared to Adium and the Aqua styled iMessage app.