That is entirely up to you, but once you uninstall it, not sure the app will still be available to you later.
I have Photos, iPhoto, and Aperture running on my Mac. Sometimes I want to use Photo for what I'm doing, sometimes I want to use one of the other apps. Since you can display your entire camera roll on either Photos or iPhoto on the Import window, you can selectively choose particular photos to import on the App you do not use as your "Primary".
I did find that recently (not sure if it was when I went to El Cap, or later) I can no longer have my Photo Stream and Shared Photo Streams set up in Preferences for both Photos and iPhoto, and if you have it set up on iCloud, it now defaults to Photos. Just worth a mention.
I believe that our resident Photo experts say that if you want to delete the iPhoto app and the iPhoto library from your Mac, to be sure that you really want to do that, and to also be sure to make a backup to Time Machine before doing that because reverting once you have made the leap is extremely difficult.
Cheers 🙂
GB