My friends with an iphone always struggle to send even a photo without Internet use, I have troubles with understanding how to upload to the iphone gigabites of MP3s. Also same questions to this device: Is it convenient to rewind files as long as 2-3 hours? Is it possible to speed up/slow down playback?
It can background download either over cellular or WiFi. You can disable Cellular downloads if it's too slow or expensive, and override it per-show (such as if you're traveling and really need the show).
You can skip silent spots and speed up the playback, and there are equalizer effects.
You can rewind files as long as 2-3 hours (I've seen shows as long as 12 hours, although I've never played them from front to back). You can set the fast-forward and rewind durations per click on a per-show basis, and allow the first click duration to be larger than the later ones.
You can control whether the show gets deleted after it's played, such as never if you want to always keep it on device because it's too big to download.
You can set a timer if you want playback to end after a certain time. It will remember the position last played in a podcast.
You can arrange podcasts by your own defined categories.
There are default global settings, and per-podcast overrides.
You can search for podcasts by keyword, or enter RSS feed URL manually. They don't have to be iTunes podcasts.
You can export podcast episodes by email/text attachments, or send raw files to other apps.
It uses SQLite under the hood, and I've used it with thousands of subscribed podcasts.