I am using a charm pack and jelly roll right now (Merry and Bright from Moda). I am making a box around the charm squares with the strips and then just sewing those blocks together, laying them out 6 x 7. (I had to make 2 extra blocks b/c there were only 40 squares and strips, but I had some yardage so it wasn't a problem.
Anyway, I love having the charm squares/strips cut already, but I don't like the pinked edges- they make me sneezey/wheezey and I have a hard time making accurate seams with them for some reason.
You have to be careful because I have gotten them and they weren't cut square. (From an Etsy seller, so I don't know if they were directly from Moda or if she had cut them herself. They did have pinked edges and the same paper around it that the "real" Moda ones have, so I don't really know what happened there. I used them anyway- just had to square up those blocks a lot.)