Summary: The sound the Driver makes is like your hitting your golf ball with a tank!
The price has dropped quite a bit since it was introduced in 2008,I believe, so if you can find one in a golf store or online - give it a try.
I chose one with the stiff flex , The regular flex has too much play in it.
Golf Driver Reviews of the Callaway Hyper X Driver
18 December 2008
Summary: The Hyper X is Callaway's upgrade to the Big Bertha 460 but still carries on the tradition of forgiving stroke play. Callaway says the Hyper X has the largest hitting area of any titanium driver they have ever made, which creates higher ball speed across the face. Our reviews of this club certainly confirmed this with shots on the toe or the heel still going straighter and longer than usual.
Conclusion: Callaway Hyper X Driver : Callaway Golf engineers set out looking for breakthrough ball speed enhancements that would set a new standard in a crowded all-titanium driver market. The innovative Hyper X Driver provides a new benchmark in performance with the introduction of Hyperbolic Face Technology, redefining the look, feel and speed at which golf balls leave the clubface.
Conclusion: This driver took almost eight years to perfect but the engineers but no waste of time here since the engineers have come up with a club face that is more efficient resulting to greater distance.
Callaway Hyper X - Why the Callaway Hyper X Driver Won My Heart…
14 May 2008
Conclusion: Yes, the Hyper X won my heart. All science aside, it makes me more comfortable teeing off than ever. I’m not a big hitter and I don’t necessarily generate a lot of clubhead speed, but this driver made be feel like I was one of the guys. Very fun indeed! I’m breaking the scale and giving it a 7 out of 5 stars. The Callaway Hyper X Driver is a winner!