New figures suggest that iPhone owners are altogether less impressed by the new iOS 15 software update than they were by iOS 14 last year - or rather, that fewer iPhone owners are sufficiently impressed to install it.

When the final public version of iOS 14.0 had been available for 48 hours, 14.7% of iPhone users had installed it, according to statistics from the analyst firm Mixpanel.

The same figure this year, 48 hours after iOS 15 was released, was significantly lower: just 8.6% of devices measured by Mixpanel were running iOS 15 after two days.

After three days of availability, iOS 15's install percentage had risen to 11.6%, which is even further behind the equivalent figure (20.2%) for iOS 14.

Here's a chart showing iOS 14 adoption across the first five days of availability, based on Mixpanel's figures:

Mixpanel: iOS 14 adoption

And here's the equivalent chart for iOS 15, showing a noticeably slower rise:

Mixpanel: iOS 15 adoption

One reason for the slower adoption may be the absence of sensational new features in iOS 15. iOS 14 added the ability to remove apps from the home screen but keep them in the new App Library, for example, and made waves with the new Home screen widget feature.

MacRumors also theorises that a recent Apple announcement - that iPhone owners can remain on iOS 14 and continue to receive important security updates - will also have been a factor, although we have our doubts about the number of users who will be aware of this change.

There have been some well publicised bugs in iOS 15, which may have put off some potential upgraders. Perhaps our advice not to update just yet influenced a couple of people, too.

Mixpanel's numbers, surprisingly, tend to be higher than the official ones occasionally reported by Apple. In June, for example, Apple announced that 85% of all iPhone users were running iOS 14, yet Mixpanel had been reporting a figure of 90.5% as early as April.

This may be because Mixpanel does not have access to data from all iPhone users, but is dependent on the subset of websites and apps that use its platform.

This article originally appeared on Macworld Sweden. Translation and additional reporting by David Price.