Does someone at Apple manually check the whole app when you submit an update?

Yes, absolutely. In fact, based on the fact that my apps frequently sit in 'In Review' (versus 'Waiting for Review') for 12+ hours usually, it wouldn't shock me if they had multiple people review each submission.

How much they play around with the app seems to vary - I've had odd, hard-to-trigger bugs get my app rejected, even though they existed for several prior versions.

Each app submission/update costs Apple a fair amount of money to review.

It definitely seems like multiple people can be involved if there is uncertainty on whether to reject the app. From experience, I've found that if my app is sitting in "In Review" status for more than a certain number of hours, it's likely to get rejected.

The only time Apple gave out hard numbers on their review setup, a couple of years ago, they had two reviewers check each submission, with an average of 6.5 minutes per reviewer per submission spent checking it. Obviously, that average contains quite a bit of variation.

They also check more expensive apps more thoroughly, according to the iOS developer guidelines.

That checks out with my experience. Typically an app will go from 'in review' to 'processing for the app store' in about 15 mins.

My app always takes many hours to review. There are a lot of buttons.

Interesting. I don't think I've ever had one take < 1 hour, and most are 3+ hours from 'In Review' to 'Processing for App Store' or 'Rejected'. 12-24 hours is fairly common for me, and I just had one approved the other day that was 'In Review' for ~48 hours.

Yes, they have human reviewers launch the app and tap around a bit, in addition to automated code analysis.

that 'automated code analysis' also let a 'Flashlight' app that was, actually, a covert tethering app go live.

As an app developer myself, I never said that it was good review :-)

We had a app finally get thought the review queue last week after a 12 day wait. Maybe there's a recent surge of apps hitting the store post-WWDC? No problems with corrupted binaries for us though.

Wow 12 days. Haven't had to wait that long for a few years now. Probably also a slew of updates due to developers updating keywords caused by the recent change to the App Store search algorithms.

http://news.ycombinator.com/item?id=4153610

Updates to my main app usually took between 3-5 days. The last update took 28 days. (just released one week ago)

another source for submission times http://reviewtimes.shinydevelopment.com/