I semi-frequently carry a 5th-gen iPod touch for music (mostly with Groove), podcasts (with iOS podcasts app) and mapping (mostly HERE maps for offline capability), since my 32gb WP doesn’t have the storage space for these and it saves on phone battery. Don’t often use any other apps, there isn’t really anything I care about that isn’t available on Windows Phone.
* iPod Touch is really a beautifully built and minimal device. 4" screen and 6.1mm thick.
* iPod gets 3-4 days of battery life of fairly heavy use, vs. <1 day for phone.
* Wifi passwords don’t sync from Windows devices to iPod Touch.
* iPod Touch doesn’t have GPS, so navigation in non-urban areas isn’t very useful, but geo location with Wi-Fi is good in urban areas.
* Stock keyboard on iOS is shockingly bad, and third-party keyboards don’t integrate seamlessly.
* 5th-gen iPod Touch is very slow.
* Safari is kind of dumpy, but not really an issue for me since 5th-gen iPod Touch is too slow to sensibly browse web anyway.
* Will order a 6th-gen whenever they become available refurb, since new iOS products are too expensive.
* OneNote (and other MS products/services) syncing on iOS is good.