I actually like the new Hangouts better, but I wasn't much of a GTalk user before... what was lost that people are trashing this?
That being said Google did IMO severely cripple their Navigation software for cars when they rolled it into Google Maps. Now it is unintuitive and can't just go into "car" mode without providing a destination which is extremely lame. Maybe I'm using it wrong but before it was just a matter of bringing it up and it was useful, now not so much at all.
How funny, we have contradicting opinions on maps navigation!
What I notice in hangouts vs. gtalk is that hangouts is no longer an instant-message-oriented thing. You can also no longer set your status manually (only "mute" notifications). Hangouts on android devices is extremely frustrating because it did not properly show your chat contacts (and was just a mishmash of your G+/gmail contact list). The main purpose for "IM" is to talk to someone instantly. But with Hangouts, you don't know if your contact is actually online and available to chat (for example, their status might be denoted as amber, but you don't know if it's because they briefly stopped using their computer, or have "muted" their notifications for 2 days--in one situation, they'll get your IM immediately (if they're briefly away), in the other they won't get it until 2 days later, but you'll never know.
I found the dumbification of Maps/navigation actually simpler to use. I never sawa purpose of designating the transportation mode unless needing navigation directions--so migrating that option to navigation makes sense. Although I don't like how it's now an outlet to throw commercialized ads at you (based on location, you may like "this" nearby).
I do NOT like how maps removed the zoom in (+) and zoom out (-) buttons. I wonder if it was a way to discourage people from using their device while driving (because without the buttons, you cannot zoom in and out with a single hand--you need to hold the phone, then pinch to zoom).