I use cream shadows and eyeshadow pencils/sticks the same way: as both a color in and of themselves, and as a colored cream base to accentuate a given eyeshadow. Eye pencils travel a bit more easily, since you don't generally have to carry a separate applicator with you; and for the most part, eyeshadow sticks and pencils seem to come in a wider array of colors. Cream shadows have a smoother consistency, though. You also don't lose product when you sharpen a cream shadow. Both have their better points. I've got a heck of a lot of both.

I love cream shadows. I still have to use a primer under them to keep them from migrating on my oily+hooded eyelids, but I love how even a “neutral” or “invisible” cream base can really amplify any eyeshadow. Even more, I love that Maybelline has their Color Tattoo line and that they're permanent - MAC's Paint Pots are lovely, but the permanent range is somewhat limited in terms of shades and they're USD$20 a pop. I'm also saddened at Benefit's decision a few years ago to switch to the less-airtight plastic containers with domed lids. They look cute and the packaging style visually matches the rest of their line, but they aren't as easy to store stacked (like the other jars were) and the product dries out faster because the containers aren't as airtight.