Upgrading from PS4 to PS4 Pro. Is it worth it?

The console itself is pretty much the same, works identically.
The only difference is the fact PS4 Pro supports 4K resolution. Even though it still isn't true 4K. Runs around 3200 x 1800 lines then its basically up scaled so there is a difference but it's still not 4K.
The GPU is uprated to allow improved quality of texture and lighting.
But yes the hard drive is larger, but for a n upgrade like that you're better off buying an external hard drive and formatting it for the PS4.
In my opinion, until they actually release a 4K console it's not worth the jump for now. PC's that run 4K cost 4 or 5 times more than a console as the rendering required to make the game run smooth is enormus!

PS4 Pro has a bit better graphical performance and better resolution. You will definitely see a difference on a 4K TV, but it will be far from being perfect.

Best regards,
Helen

I changed from standard to pro on a 4K tv, can’t say I was blown away by the difference tbh

Probably best waiting for PS5, minimal gains from PS4 to PS4 Pro on 4K TV.