It will raise your bars 20mm, which may be a good or a bad thing depending on your existing body position on the bike and what you like. It's also going to slacken your head angle about 1*, which is noticeable.
Kevin is right, it may make steering a little more sluggish at slow speeds, but it's also going to make your bike more stable at speed (less twitchy. This will b)e beneficial on rush and other steep and fast trails. There's a reason a lot of newer bikes are way slacker than bikes even 2 years ago.
The longer fork will also raise your bb a hair, and will make your seat angle 1* slacker (both bad things). That means when climbing steep stuff seated, your center of gravity will be pulling you toward the back of the bike, making it want to wheelie a bit more. You can slide your saddle forward in its rails to compensate for this.
Do you know what your head angle is right now? In my opinion, most hardtails benefit from a slacker head angle on fast and steep terrain.
