I upgraded from the 14 to the 15 Pro (not the regular 15, but some things still apply). Honestly, if you're coming from a 14, the regular 15 isn't a massive leap. The camera is a bit better, especially in low light. You'll notice a difference, but it's not night and day. The Dynamic Island is kinda cool, but after a week, you barely notice it's there. Battery life is supposedly a tad better on the 15, but again, we're talking marginal gains.
If you're on a tight budget, stick with the 14. It's still a fantastic phone. If money isn't a huge issue and you want the slightly better camera and Dynamic Island, then go for the 15. But manage your expectations. It's an upgrade, but a fairly incremental one. I would only make the jump if you can get a good trade-in deal on your 14.
techfan101: The Pro's 120Hz display is a noticeable improvement, especially if you're scrolling through social media or playing games. Everything feels smoother.