[emef]

This used to be the case, but I'd argue not as much anymore. I had the 3gs for ~4 years and by the end it was nearly unusable due to updates (noticeably worse every time). I'm now nearly at the 5 year mark on my 5s and on the latest ios, no problems. It's not as snappy as my wife's new phone but completely usable.

[astrobase_go]

i would agree here. both of my parents and the wife have just as much time logged on their full-updated 5s' as well and, save for foreseeable decrements in battery performance, they think their system performance is generally indistinguishable from new.