Since I just moved to a storefront location, I'm probably a good person to answer this.
Pros: TONS of exposure. I chose to open the studio in my hometown which is about 10 minutes from where I live now and in Iowa. I have a very small space right smack dab in the middle of town and right near one of the most popular little Cafes in town. There is a lot of foot traffic. I don't think it is the location alone getting the exposure. I also joined the the Chamber of Commerce and contacted the newspaper who ran a story about me. I've also had quite a few WOM referrals trickling in lately, but I do think the studio location makes me appear much more credible. It also makes me feel like I can really say that this is my job and I am a professional.
Cons: Too much exposure? I thought I knew what I could handle, but I have had some health problems and major computer issues which has put me behind quite a bit. I have things sorted out now, but I am still playing catchup.
The overhead would obviously be a con, but mine is very minimal at this point because the studio is so small. I am working on tweaking my business plan and running through all of my financial info to try and find out what I would have to do to get into a larger location (if business stays as good as it is.)
If you plan on having set hours (heck, even if you don't) you need employees. At least one anyway. I spend at least 2 hours a day playing secretary and really should be spending more than that (I'm still a little disorganized at this point.) It is very hard to juggle all of the roles that you will have as a business owner while keeping you clients happy.
Being away from home. I have spent a lot of late nights working and miss my hubby and ours dogs a lot! I will be getting a laptop so I can work some home, so that problem will be solved.
Overall, I agree with Jessica and Wendi. If you are going to get a location I would probably be on the lookout for an actual commercial location. However, if you don't have anywhere else to shoot I would strongly consider the garage situation, as long as it is adequate for what you need.
Hope that helps a bit.