I hadn't played it in a while, but I booted it up again recently with the update. I'm still not sure how much I'll get back into it, though, and it seems kind of dead around me. My main issues are:
1. It's banned at the location where I spend most of my time during the work week (and has been since the summer).
2. My phone is getting to be on the older side, and the battery life isn't great. Pokemon GO kills my battery too much.
3. I was having too much trouble getting it to track my steps properly, and that made it hard to hatch eggs. Now, the egg spawn rate seems lower than before, so I'm having trouble getting more eggs to hatch. I also liked using Pokemon GO to get a sense of how much I was walking, but I got a Fitbit this fall, and that obviously works much better for that purpose.
4. I didn't really hit the ground running at the beginning (couldn't access the server for several days at the start when other people were leveling up, and never really caught up). Because I've been behind the curve from the start, I've never stood a chance at gyms, so I pretty much just catch Pokemon when I have the chance. It's fun, but given the other issues I have, I tend to spend more of my free time playing "real" Pokemon games instead.
I think the weather probably isn't helping Pokemon GO much. In the summer, people are happy to walk around and catch Pokemon. In the winter, though, it's colder, and people don't spend as much time outdoors (and definitely don't want to have to hunt down Pokemon). If there's another update next spring, I could see it catching on again, though not with the same degree of hype as the original release.
For now, I'll continue adding to my Pokedex when I have the chance, but I've also come to terms with the fact that I'm unlikely to every complete everything I would like to in Pokemon GO. As a completionist and a perfectionist, my inability to near that goal bugs me a bit, and leads me to spend more time playing 3DS Pokemon titles, where I know my efforts will pay off if I put the time in.