Great interface, push notifications are fast, and messages update quickly when chatting with someone. And its just overall simple and easy to use - not too much, not too little.
I used to use IMO til they started over complicating things and tried to make me use an IMO-specific account rather than my google account, then I switched to beejive but that had some serious lag with chats not showing up in the app til a minute after the push notification came through, so I tried this app even though it had no reviews at the time, and its been great! I couldnt ask for more!
Kurose about Katoo for Gtalk Hangouts