Sure man! The major differences from the GoPro HD Hero 2 and the previous model are:
The GoPro HD Hero 2 has
1) New LCD menu system - Easier to navigate the menus
2) 2x Sharper Glass Lens - What this means is that, for the most part, your images will be cleaner and crisper
3) 2x Faster Image Processor - Notice with your GoPro when a video is taken it usually takes a second or two to actually register that it was taken. A faster image processor will cut down on this time.
4) 11 mega pixel sensor - Pictures are now taken at 11 mega pixels which means there are more pixels in your image. Essentially what this does is it "usually" allows for better image quality as well as allowing the user to blow up the size of their picture. Disclaimer - more megapixels doesn't necessarily mean better image quality, but in this case I believe it does.
5) Mini HDMI port - allows you connect your GoPro to a HD T.V.
6) LED lights on all sides - have you ever looked through footage and found a ton of videos and photos where your just staring at the camera seeing if its recording? This feature eliminates this problem because now the red light is located on every side of the camera making it viewable from all angles.
7) Wifi backpack + Wifi Remote - Allows to wirelessly control whether your GoPro is recording or not with a handy little remote
8) 3.5 mm stereo external mic input - This basically allows you to connect a separate device to capture crisper audio
9) Integrated Battery Warmer - Allows the battery to last longer in colder temperatures. Especially useful when skiing!
10) More photo and video modes - Photo = you can now take 10 photos in the span of a second and in time lapse mode you can have it take photos every 0.5 of a second. Video = WVGA resolution at 120 frames per second. WVGA just refers to standard resolution.
I know a lot of you want to see a side by side comparison of the new model and the old model and so do I. But in the mean time, look at the following videos. Im sure all of you have seen the first video, but watch it one more time in 720p. Pay close attention to the quality and sharpness of the image.
Now watch this in 720p. (GoPro's last posted video with the original HD Hero)
In my opinion the original HD hero doesn't look as crisp as the GoPro 2. Whether this increase in quality and features justifies a upgrade, that is completely up to you!
Personally I don't use my GoPro that much because I have a Canon 60D, but for me, all of the new features as well as enhanced image quality make it seem like a worthy upgrade and would most likely prompt me to use it more!
I hoped that helped!