Do I want cadence on my computer?

[OakLeaf]

I think it's useful on the flats and downhills, too. You can practice spinning at a very high cadence, and also know when you're unintentionally spinning up higher than you want to.

[NadiaMac]

I think cadence is an optional feature. Sure, it's nice to have, but you can also estimate it using your computer clock and counting. It's easy to see whether you are at or below 60 rpm, at or below 90 rpm, at or below 120 rpm, etc, by counting ~ 1, 1.5 or 2 revolutions per second. After a while of doing this on the trainer, I am actually pretty good at estimating ballpark cadence while on the road. (I've verified this using a powertap wheel occasionally while on the road).