Are All Free eBook-Gen Sites Equal?

Fellow indie-published authors, as I am about to embark on my first journey into the world of ePublishing: (a) What should I be leery about when reading through the Terms and Conditions (T&Cs) of various websites that offer free eBook-generating and eBook marketing services? And…

(b) Other than varying commission rates and varying eBook cover graphics specifications, what major differences have you found between these various online services? …especially buried within the darkest depths of all the legalese? Please share good and bad experiences, particularly working with Smashwords. (I like that Smashwords will put your eBook all major markets which sounds like a big help to a busy little indie author like me. But, is there a catch?)