I got my phone through T-mobile's deal of $0 down and pay over 2 years. It's my first iphone switching from andriod. At first I was worried about missing out on the 5s features and that it would be quite small compared to HTC One and other Samsung phones, but I think it is the right size for convenient single hand usage. A bigger screen may be welcome in the future for better movies/gameplay/document viewing but it's certainly better than the 4s screen size.
I finally went to an Apple store to see the 5s that I "missed out" on. I found out I actually preferred the 5c to the 5s because of how comfortable it felt in hand and the slight additional weight of the 5c made it feel more substantial and durable. The 5s was also less comfortable to hold due to the sharp edges and felt "cheap" because of how light it was. I was also kind of turned off by how the 5s looks after being used for so long - the demo models were a bit scratched/grimy not very bright/shinny/attractive. On the other hand the 5c "ages" well. I also tested responsiveness and speed of the user interface and was not impressed. It was exactly the same as the 5c. Probably larger apps and other computation would load faster, but general things like scrolling through menus, opening webpages was no different. Next time I'll have to try something more graphics intensive and report back but it does say a lot about the 5c.
Functionality, speed and ergonomics are all there with the 5c. Another thing worth mentioning is that the 5c is the less "flashy" phone and that was important to me (at least the white version) since I am not looking to standout and since there are a lot of phone theft/muggings/robberies these days. So overall, I feel this phone fit my needs perfectly.meizu-mx5.com