Although comfortable, clean, and well-equipped, and close to a good hiking trail and the dunes, the "guest house" for this rental lacks many of the key amenities that make the larger property seem attractive. There is virtually no view from the guest house (the guest house is over a garage facing a suburban street, rather than the dunes or the lake) and has no real deck. Given that we were paying a rate appropriate for a lakefront home with a view, this was disappointing to us. Miller Beach is also a very industrial part of the Indiana lakefront in a part of Gary that has seen better days, so be aware of that. (We have stayed at other rentals in Indiana in towns such as Porter Beach, where you also see the power plants and the steel mills, but they are much further away so the setting is quite different).
Can't comment on the main home, which seemed nice from the outside, but for smaller groups renting only the guest house just be aware of what you are getting, and not getting, for the rate. If you know the area and like it, and rent the full house, could be a good option. But this was not an appealing property overall for our interest in a lakefront rental with a nice view for 2 people.