My girlfriend and I stayed at the Amberley Guest House whilst visiting a friend who happens to live a few doors down the road from it. Though we were only there for one night, we were made to feel very welcome and comfortable by Eliana who is so lovely you almost feel like you've been welcomed into her home. Our room was very nice and comfortable, breakfast was great and the car park at the front made life a lot easier than it otherwise would have been (parking in this area of Southampton being at a premium, based on my previous experience). The guest house is also in a good location for venturing into the centre of Southampton and getting to the nightlife areas.
I will definitely be staying here again on my next trip down and would recommend it to anyone.