GREAT shoe! Dare I say the BEST shoe I have ever ran in. This is a complete re-design from version 3. Hyperburst on the lateral side which creates a soft landing, and ultra flight/flight gen on the medial side which slows pronation and results in a propulsive toe-off. I am pretty sure (not 100% on this) that this is the lightest stability shoe on the market as well. I'm a severe overpronator with moderate PTTD in my left foot. I have spent a lot of time testing out different shoes, trying to find something that is both stable and light, which is easier said than done. Once I am done putting enough miles on my NB Vongo and Hoka Arahi, they will be permanently replaced by the Forza for all training except specific speed workouts (I prefer the Razor 3 for that).
If you crave a shoe that is both light and stable, while also being soft and propulsive, this is your shoe. I'm sure it would work quite well for 'neutral' runners as well for those longer runs where your form starts to get sloppy towards the end. For everyone else, the Go Run Ride 8 is probably enough. Nonetheless, I train in the GRR8 too and I LOVE the Forza 4 way more.
Current rotation: Skechers Forza 4, Razor 3, Ride 8, Hoka Arahi 3, NB Vongo v3, and Asics GlideRide. The only ones I plan on keeping in my rotation moving forward are the Forza, Razor 3, and the GlideRide.