I've used several packs and found it well-nigh impossible to get consistent results. However, there are a few 'rules' to up your chance of getting something presentable. You need to cover from light asap, then you need to keep them dark for a while too. Temperature changes also affects the colour etc. Some people have reported fading of images over time - I've kept mine in a dark box and they've been ok so far.See hints here, and also look at the Flikr group for hints
I've posted a couple of my more successful shots in the APUG Polaroid/Impossible group. You have to remember though to expect quirks, mottling, strange exposures etc...
Hopefully subsequent versions of Silver Shade iron out some of these issue.
Hope this helps,