iPhone 5s - worth getting or avoid?

[Broken Hope]

This. Support is one thing, proper optimisation is another.

iOS 10 is nice and fast on my 6 and the 5S isn't much slower.

 

[CorrectHorseBattery]

Aren't the 5s and 6 pretty much identical inside?

 

[OspreyO]

Aren't the 5s and 6 pretty much identical inside?

No. Similar performance though. Different chips.

 

[Broken Hope]

Aren't the 5s and 6 pretty much identical inside?

Completely different, just the A8 wasn't a very large performance increase over the A7, the A9 was a massive increase over the A8, it will be interesting to see how much faster the A10 is.

 

[CorrectHorseBattery]

I think the 5s might be supported for some time yet. It should maintain its performance too, being 64 bit.