To photograph the interior of a home is MUCH more complicated than shooting the outside. Window shots are very important when photographing a home, and sunny days can make this difficult, leaving you with a blown-out, hazy effect. As we cannot control the weather, this can be combated in a few different ways: speedflash or onboard camera flash, HDR processing & hot lights (which stay on) to name a few.
Upon reading I came across this great article going over the pros & cons of these methods & more.
Personally, I am having few issues with the speedlight I am using. One of the cons for speedlights and flashes are that you are left with bright reflections everywhere, not very pleasant looking (especially in a panoramic). To ensure you dont get that, be sure to bounce the flash straight up to the ceiling & leaving you a great shot with balanced lighting & clear windows. Also a diffuser of some sort is invaluable if you are using a flash. This means you can point your flash directly where you want it (mainly used for portraits) and have the light evenly distributed. 
Lighting is just ONE aspect to real estate photography and having someone with the experience of knowing how to achieve the best photo of a home given any situation is key.
