There is something different about a face-to-face interview. You get to see the facial reactions of the guests when you ask them a question (for better or for worse). You can also tell by their body language if they are into the interview or disinterested. Conversely, the guests can tell the same things about how you are reacting. Doing a face-to-face interview is also very intimidating for someone new to doing interviews. At least with a Skype interview there is some security in knowing the other person cannot see you sweat or realize how nervous you really are. However, some podcasters really love doing live face-to-face interviews. Andrew from Exit 50 is one of these people, and he had this to say about doing these types of interviews:
Also remember that depending on the surroundings, the audio quality can vary from the best to the worst. If you and your guest are face to face in your recording studio office, chances are the audio will be pristine. However, if you are face to face in a sports bar on a Sunday afternoon in Kansas City with the Chiefs playing in the background, there is a high probability that the audio will be barely understandable. So when you pick a location outside of your normal studio setting, if at all possible you should scout out potential interview spots to see what type of background noise you will be dealing with. There is nothing wrong with a good man-on-the-street-type interview as long as it is more man and less street.