Even though Hornady have some excellent marketing, I have bought into the hype every time lol and I Havnt been dissapointed.
I shoot creed and 6.5 PRC and I love them both.
I can't see the 300 prc being any different as it's a ground up design for long range precision shooting, predominantly purposed for over 1000 yards shots, with the main advantage being appropriate bullet seating from the get go (sammi specs are on the money so manufacturers can legally produce high end boxed ammo)
YES you can achieve simialir if not same performance from a win mag or one of the others by reloading and building rifles to suit. However, the PRC is going to be an off the shelf, out of the box solution for the heavy for caliber Bullets out and soon to be released. Move with the times and enjly it I say.
I'm currently Building a Norma but i think once one of my 28's are shot out I'll go a 300PRC and drink the cool aid