in my line of work, the same problems come up all the time.
1. Terrible briefs. From Client. Exacerbated by terrible briefs written by Client Service.
2. Work off brief (um, go figure).
3. Creative takes too long (see above comment).
4. Too expensive (yes, there it is again).
5. Poor relationship (well it would be wouldn't it?)
So I love AdCracker because it shows anyone (client or agency) how to write a good brief, what a positioning is, what should be in a strategy, some clever insight into consumer behaviour.
But best of all, it attempts, through CD Steve MacNamara's personal and light hearted writing, to teach people the difference between a good ad and a mediocre one. He showcases great ads, and tells you why they work.
Every agency, and every marketing department should have one, and make it compulsory viewing.
In my humble opinion.