Didn't like the new Photos app, but it is only the removal of the Events view that throws me off. I have a lot of Events, and Photos smushes them all together. Ugh.
Herblock's Law: If it's good, they'll stop making it.
I downloaded the beta photos app right when it came out and ended up deleting the old iphotos app shortly after. Photos is much better. Loads much quicker, cleaner UI, maps integration is much better, and photostream is more seamless.
iPhoto served a purpose but I was a user of Aperture and what Apple did to that app turned me off of Photos (gutting the functionality also pushed me away). Apple's track record for image apps is poor and as such, I've moved on to Adobe's Lightroom.