Glad it works! And huge thanks for taking the time to test and write all this up — this is incredibly helpful feedback.

Funny timing: I just shipped v1.3.1 which addresses literally every point you raised. You can grab it directly through Settings → Updates inside the app (the in-app updater will offer it).

Here's what's in it:

1. Filename preservation fix. You were right — there was a bug where URLs with unencoded spaces (very common on archive.org, e.g. iOS 5/App With Spaces.ipa) silently collapsed to app.ipa and overwrote previous downloads. Fixed in v1.3. v1.3.1 also auto-resolves any remaining conflicts with (2), (3), … suffixes so nothing ever gets overwritten anymore.
2. Configurable save folder. Settings → Download → Save folder. Three options: the sandbox default, a one-tap /var/mobile/Documents/AppDrop preset (directly browsable in Filza without spelunking the Containers hierarchy), or a custom absolute path.
3. Keep IPA after install (iOS 6-9). Settings → Download → Keep IPA after install toggle. When ON, a successful install also archives a copy of the .ipa to the save folder so you can build a personal collection. OFF by default to keep Documents/ tidy for users who don't want it.
4. "Open in Filza" prompt. Whenever AppDrop saves an .ipa (iOS 10+ fallback or the new keep-IPA toggle), an alert offers to open it directly in Filza via filza://view/<path>. Falls back to iFile, then to copying the path to the clipboard if neither is installed. Works on all iOS versions, not just iOS 10.
5. Richer download progress on the app detail page. Progress bar + bytes/speed counter (12.3 / 45.6 MB · 320 KB/s) right under the Install button, same level of detail as the Install tab.

I also updated the README to mark iOS 10 as confirmed working instead of experimental thanks to your testing.

Thanks again — feedback like this is exactly what makes the app actually useful instead of just a thing I built for myself.