When I started working, GTalk was also an easy medium to get in touch with my colleagues and others for work-related issues. I preferred talking over GTalk than answering calls as it was convenient and time-saving. My Android smartphone made it easy for me to chat with anyone, anytime, anywhere, even when I was away from my laptop.
Things, however, changed when Google decided to unify its real-time messaging applications across devices. It replaced the GTalk with Hangouts. I personally didn't like the interface of Hangout and found it more difficult to use primarily because there wasn't any proper display of my contact's online status.
I wasn't sure if he/she was online, checking my messages. This was later fixed with a green circle for people who were online for the browser, but not for the mobile app. The biggest luxury of using a GTalk was the invisible mode where I could chat with a few contacts I wished to communicate with, without offending others. It was the time, when I stopped using the Hangout and signed off completely. While I missed using GTalk, WhatsApp, another messaging app, filled the gap and replaced both GTalk and text messaging for me.
Now, when Google has finally stopped its GTalk services and replaced it with Hangout, it doesn't really matter much as for me, it was dead long ago. And I am not alone. Most of my contacts who used to stay connected using GTalk, have, like me, also moved to WhatsApp and with its browser client, things seem to be much easier.