I've got time to kill while I wait the 2 day delay trying to fly back to Chicago, so here's my review of the transfer from Verizon iPhone to Ting Nexus 5.
Cell Phone Reception / Service
I was expecting Sprint/Ting to be slightly worse than Verizon and that's about what I experienced. I don't travel that much and fortunately in Chicago Sprint has been good with coverage as good as Verizon. On the road, Sprint's been OK with just a couple of times not getting signals/roaming where that wouldn't have happened with Verizon.
I have one text message that won't send despite retries and it's unclear if it's the service here, the phone, or my recipient's phone. In any case, this happened rarely with iPhone, and as I'm new with the new setup, it's unclear if this is a pattern or a fluke.
Phone itself
Overall like the Nexus 5 over the iPhone. Much faster interface and lighter. The fact that the phone is bigger than the iPhone 4 is a little bit of a con - it doesn't slide in/out of a pocket as smoothly as the iPhone 4, but if you put the 2 side by side and asked me to pick one phone for the next year, I'd pick the Nexus 5. I'm waiting on a case & protective skin to arrive and will try that out. The lightness of the phone and its form factor makes it seem more fragile, but this is probably 90% mental.
I haven't tinkered much with trying to optimize battery life outside of the factory defaults with the phone. Battery life is a little better than iPhone 4, but it has not made any substantive change to how I manage the phone... like the iPhone, I have enough juice to get through a day without a worry about running out. If I don't charge overnight, I would have enough to cover the morning, but I'd have to be a power miser with it on Day 2. Looking forward to the wireless charging station which should be waiting for me at home.
iOS to Android
I posted elsewhere in FFA that I've had the same kind of difficulties getting things switched over (getting out of iMessage for example). Now that I'm pretty much set-up and things are humming along, I will say it's a mixed bag of pros/cons, but mostly the pros outweigh the cons. The speed at which I can do 'the basics' - text, read email and do quick google look-up is way better than iPhone. There is no app that I had on iOS that I miss (outside of Downcast for podcasts - I haven't found one as good as that). I like that things can be customized - for example, I wasn't a fan of the hangouts app, so... no problem; google other SMS apps, read the reviews and try a couple of other SMS text apps out for size. That couldn't be done on iOS.
There are still some cons with Android. I can't get attachments that come through Yahoo mail on the native mail app. I realize that the solution is "just use Gmail", which seems like not much of a solution since I have 15 years history with my Yahoo email address and I actually prefer Yahoo interface over Gmail on a PC. Another gripe is that html links don't always show up as clickable links. Sometimes they do, sometimes they don't. This was never an issue with iOS.
I know there's more that I could do with a smartphone, but I generally don't like the smartphone to alert/notify me of stuff. I look to the phone when I have time or have a pressing question.
If I was a heavy Google guy (Gmail, Google+), the switch would have been awesome. As I'm not, the switch is generally good, with some caveats.
I haven't had a full month's bill yet, but they are projecting me at $31/month, whereas I was at 95/month with Verizon. I will put my wife on our plan with Ting and expense the whole monthly bill. With that in mind, I'm glad I made the switch and would do it again.