The app itself is nothing too fancy as it merely clears temporary data out from your phone to make room for the update in addition to checking for that OS upgrade. That first part is critical for devices with low amounts of internal memory like some budget Lumias.
From the app description:
"Update Advisor can help check if an update is available for your phone and free up space to get you started. It connects to the network to check for new updates, then helps you free up space for updates by recommending files that you can move to an SD card or OneDrive to make room for the update. After the update is completed, you can move the files back to your phone.
With the Update Advisor app, you can:
- Move songs, podcasts, pictures and videos to your SD card.
- Move songs, podcasts, pictures and videos to OneDrive.
- Delete songs, podcasts, pictures and videos from your phone.
We just ran the update on our Lumia 640 with Windows Phone 8.1 and – no surprise here – there is no update waiting. Still, if you think you may find value from the app feel free to download it and keep it by if and when those OS updates begin to roll out starting next week.
Thanks, Sudesh B., for the tip!