It's definitely improved, in the early days apps could be stuck for months with no communication. Even still, the company I work for (a top 50 communications app) submits updates every 2 weeks, we get bogus rejections about 50% of the time. Literally yesterday we were rejected because they claimed the app blocked installs on an iPad. We replied that it doesn't, and has never done that. They then approved it the day after (Same build, we made no changes.) Literally a waste of everyone's time. This happens at least once a month. We've been also been rejected for accepting promo codes, using apple's official promo code entry screen because the reviewer didn't know that it existed and said it was against the guidelines.Smaller app developer here. fwiw I recently submitted a new game to the App Store, preparing myself for a multi-week wait. The initial release (which I submitted on the weekend) was approved within 2 hours, and all subsequent updates have taken less than 30 minutes to approve.
So in my experience, at least, I do think the app store approval process has improved tremendously over the last 5 years.
Basically app review is 99% policing paywall copy (Using rules which Apple's own apps don't even comply with), 1% stopping scams/buggy apps.