At the top competitive level especially having Portals in a FPS makes for interesting, intense, and fast paced games. It also makes camping essentially impossible.
I looked this up on steam and noticed it's f2p, have you noticed any negative impact from that?
For me, a Portal shooter would include stuff like grenades, gun nests, smoke bombs and flashes, guns that are really heavy and slow you down, etc. Stuff that would reward maneuvering and outsmarting your opponent, ambushes, and lateral thinking.
Gameplay hightlights would be the moments where your opponents thinks they're sneaking up on your by shooting a portal behind you, only for you to sneak up on them because you knew they'd come out of that portal; sniping someone through their own portals, etc.
Splitgate just feels like an arena shooter with lots of teleportation.