I've been in Perth for two and a bit years now. I work in Exploration (mining industry) so on a reasonable wage and my standard of living is pretty good and bestter than when I was living in the uk however I still consider the cost of living to be quite high, especially the cost of renting anywhere near Perth CBD.
There are things I like about Perth, the weather is pretty good etc
But there are a lot of things that irritate or niggle. The general background casual racism, ignorance or plain hatred of immigrants (from a country of immigrants...) the inability to drive to any kind of standard.
I came out here on my own and have found it very difficult to get settled and make friends etc, part of this is be cause I work away a lot but as friendly as the aussies are I've always found hard to make new friends out here. In fact I can count on one hand the number of people I would call friends and most of those are ex-pats. I guess if you move with a family and have children in school etc that will be less of a problem.
If you don't get a car through work as above then the costs on them can be expensive. The purchase price of a car out here is relatively high and they seem to hold there value. You regularly see sheds out here that would a be a couple of hundred quid in the uk for sale for a couple of thousand dollars.
The police are pretty militant. There isn't a '10% over' allowance over here you speed and you will get a ticket for as little as 3km over a 60km limit. Road llayout is ok, traffic is often heavy not helped by the australian inability to move to the left lane, especially the freeway. Apparently the idea is pick a speed (way below the limit) pick whichever lane you like and stick to it and **** everyone else. And iif you do change lane only indicate when you get there.
Riding wise, if you are a avid downhiller then don't bother. There are a couple of local spots but there are fairly flat. One of the better spots only 1.5hrs from Perth is being felled and then the next closest places are 2-3hrs away. The only bonus being is you can shuttle them which beats walking.
Trail riding I havent done much but there is much more available than DH. Its hard work in the heat of summer and you'll have to get used to riding on pea gravel (basically small round death gravel)
I don't think I'll stay permanently. Yes I like my job and the wage gives me a good standard of living but riding and friends are more important and to be honest Perth is just too damn flat!