I've just come back from a holiday there, staying with friends. I loved it, my wife loved it we want to move there! The beaches are lovely, the marina is lovely, good parks for the kiddies and there seemed to be plenty to do. There are certainly a few Brits about, but I think that is due to affordability of the area as well. I have to say I met a lot of friendly aussies at a local school when I dropped my god daughter off, so there must be a few about! I even quite liked the travel into the city via Transperth, it is a lot cheaper than UK transport!
Obviously for me it was still a holiday and this needs to be factored in to my rose tinted view!