The new piece of furniture will be great in our house. Maybe because it will look great, maybe because it will be very useful and get used a lot I didn’t have enough chairs for visitors to sit on in my living room, so the new one I just bought will be a great addition.

In that sentence, "great" suggests that the addition will be very good or beneficial for your home. It conveys a positive sentiment rather than implying size or extremity. So, it’s more about the quality or value of the addition.