Jennifer is correct about the FHA appraisal being more strict, but it is not severely so. An appraiser's primary job is to evaluate what a knowledgable, willing seller and a knowledgable, willing buyer would agree upon for a price when both are acting in their own best interest.
His evaluation of the soundness of the property (beyond its effect on value) is limted to obviously apparent issues. In other words, the appraiser will likely not concern himself with structural issues unless he sees obvious deficiencies that would lead him to do so. Have a lot of large cracks in drywall or exterior walls? Expect him to report that there may be structural concerns. He is not an engineer, plumber, electrician, heat & air expert, etc. and will not pretend to be.
Overall, you should not have much concern with a buyer using FHA over a conventional loan. In fact, with the state of underwriting and the difficulty of obtaining mortgage insurance today, it could be said that a buyer that is using FHA financing is more assured of closing than one with conventional financing and less than 20% down.
If you have any specific concern not yet addressed, do not hesitate to ask.
Fairway Independent Mortgage - Tulsa