Others have chimed in on this as well. Good to see that in addition to the bug fixes, Apple seems to have purged some unnecessary baggage with this revision. Keep in mind that iOS 8.0 took up about ~0.7 GB more space than iOS 7.1.2 did, when comparing identically prepped devices. So, there might have already been some bloat that they didn't get around to purging until now.
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Hard to say, but I have seen other posts indicating that the update freed up a lot of storage space. Generally, a minor interval iOS update will free up a lot of space just because it purges the caches. But, if the installation file is smaller, then there might indeed be some other freed up space as well.
After updating to iOS 8.1.1, the free space on my 5s went from 7.3 GB to 7.9 GB. With a couple of days of normal use and refilling the caches (and no new apps installed), that free space is now at 7.7 GB.