I don't like:
- Transitions that take too long that could be edited out (watched a girl doing lip swatches on her lips, which is fine, but she was wiping her mouth between, which took a while, especially when she got the cotton stuck in her mouth and was sitting in front of the camera pulling pieces of cotton off her lips and tongue trying to spit it all out for 30 seconds, going "blech! ick, gross!". I'm personally fine with "ok next color!" and suddenly coming back to clean lips.)
- People who can't find the product they're looking for and spend some time ruffling through their stuff (or even saying "oh well I can't find it, I'll show you in a later video!")
- Blurry cameras. I want to see how it looks, and how light reflects off it. If the entire vid is blurry, it really doesn't help much because the colors are obscured anyway.
- background noise (other people, tv, fans, microphone that's too far away, etc)
I like:
- When people include a still image really clear picture of their swatches/final looks/before and after looks (or even in between looks)
- I actually prefer the over-information over the under-information. You never know when somebody will give you a new tip. (As long as it's relevant to the make up!)
As far as the half face thing -- Usually I've seen stuff where they're half done in the beginning and finish their face for the tut, so you can see the before and after right up front, and see the final look as it develops.