Good question; but difficult to answer.
The problem here, much like iOS, is that what Apple advertises as being 'Apple Intelligence' is really just a lot of marketing bluff. It's a way of selling quite normal features under a trendy AI banner, in the hope that consumers will expect to find them more useful than they actually are.
Machine learning and other methods of pattern learning have been around for a very long time, but it's only in recent years that the increased speed at which operations can take place have companies jumped on the AI bandwagon. Yes, it is the speed that has made new features possible since it now takes merely seconds for specific operations, but the principles really haven't changed greatly.
So I think a better question is "Has Apple's intelligence become more relevant/useful over recent years", to which I would answer a general No.
Prime examples:
Photo clean-up: Sorry, but this feature goes against Apple's philosophy of "It just works" and moves to "It may work okay, under certain circumstances". Instead of embracing authenticity and that not all photos are perfect, Apple tries to sell the idea that you can remove virtually anything you want from a photo to make it perfect. What they're not telling the consumer is that you need a more capable app, like Photoshop, and use the tools correctly to obtain a reasonable result - and even then there is some artistic license.
Writing features: Generally - turn natural language into something that... well, has clearly been written by a computer, which not only comes across as lazy but false to the reader. My attitude is that if I can't get my point across effectively, then I need to learn to write better - not simply expect a computer to work for me. Conversely, summaries can work very well and are a good example of a progressive utility.
Mail categorisation: Not useful for the majority of people who, through their iCloud account, receive a small number of emails a day. If anything it can slow down productivity and the categorising can be incorrect. I imagine this would only be useful if you received a huge number of emails each day and didn't have time to sift through the main inbox.
Mail and Messages summaries: Often inaccurate, and misses the point that many notifications are already summarised to begin with, which is why taking a summary and summarising it inevitably results in bizarre outcomes. Plus, it takes little effort to open a message and actually read it; a summary doesn't increase my productivity.
Image Playground: What could have been a great asset for images to insert into documents and presentations is a disaster. I can't even begin to describe how bad this service is, so I'll leave it there.
Genmoji: Takes more time to produce something worth sending than to just type the descriptive word or use an existing emoji. There are already so many emojis that there is no incentive to continue generating and reusing new ones.
Again, just my own thoughts and I understand that everyone's needs vary. But from my point of view, Apple has wasted a lot of time and resources in producing very mediocre 'AI' features that completely miss the point of assistance.