I have a 17 Pro coming from a 14 Pro. I miss the stainless steel and smaller camera bump. It's the same weight, but because of the camera plateau it "felt" heavier or at least top heavy until I got used to it. Overall, I'm happy with the upgrade for these reasons:
1) Now that I have a really good zoom up to 8X, I find myself using telephoto a lot more than I previously did. The 3X on the 14 Pro wasn't bad, but the 4X/8X on the 17 Pro has been really nice especially when taking video of family outdoor activities at a distance or the occasional UFO in the desert night sky.
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2) I keep all my songs in ALAC format. So having USB-C fast data transfer speeds is nice. Takes about 15 minutes to transfer my song library (11,000 songs in 2hrs15mins on the 14 Pro). Now I don't use it all that often, but having the faster transfer speed is very nice.
3) I'm not usually one for gimmicks, but the 3D Spatial photos and ability to add Portrait effect to photos after the fact is handy. I don't recall if the 14 Pro did this or if it requires Apple Intelligence. But some photos just for fun I'll add the Portrait effect and sometimes the photo looks better that way than the original. Again, nothing by itself worth upgrading for, but a cool convenience. I think I'll also add all the various little Apple Intelligence things here as well. I don't particularly care for AI but the photo cleanup has actually come in handy once or twice to remove elements from an otherwise nice photo.
4) Battery life! This list isn't in order of importance, but I will say that the battery is phenomenal. Much better than the 14 Pro. Yes, 5G would kill my 14 Pro battery, and even on the 17 Pro, it does eat into it, but because the battery is so much better, even with 5G on the 17 Pro, it's an all day battery. Having said that, 4G/LTE is fast enough for my needs, so I usually keep 5G turned off and I'll easily go two days on the 17 Pro without a charge with 5G off (1 1/2 days with 5G). This will probably be the first/biggest thing you notice. At least I did.
Final thoughts: Aluminum sucks after stainless steel and titanium. As
@Macdctr says, get a case (I like the Spigen cases because they cover the entire camera bump). And the overall build/design feels more utilitarian than fashionable. I don't buy phones to be fashion accessories, but I did come to appreciate Apple's previous eye for detail. The 17 Pro feels (to me) like an unfinished experiment (hey, let's just focus on performance and features, and figure out how to smooth it all out later). It's not as elegant, but it still is a great phone. Then again, I'd prefer all this great tech in an iPhone 5S chassis. That would be my ideal phone chassis... with titanium instead of aluminum and flush cameras.