for anything like Play Store, yes, it only requires a ROM with Bluetooth Tethering enabled. but for the notifications, S-Voice, weather clock, etc it only works on Samsung phones with TouchWiz/Gear Manager. so unless you pipe calls through GrooveIP on the watch, which in my case didn't work due to the slower speeds of BT Tethering, you won't get texts or calls unless you got a proper handset with Gear Manager running.
rooting is done mainly for apps, like apps that are not normally available. but unless you like downloading Play apps or playing games over a dial-up connection, which is what it amounts to, or struggling with Candy Crush Saga on a 1" Screen, it's not worth the disadvantages of it being seemingly one-way and killing your ability to get updates to the OS that adds features these watches have lacked when launched, such as the ability to read notifications on the watch. when i rooted my OG Gear, it was before the update to allow you to read notifications on the watch, and since any attempt to unroot and flash stock has failed, i am stuck with a watch that still has 'show on device' to read them. i wish i never rooted it.