Just don't rely on it too much. In Class G ATC has no requirement at all to give traffic information VFR to VFR, and if they are busy, they won't. You won't hear Sydney Radar giving traffic to VFR aircraft in the training area because there are too many aircraft. That's the problem - this alerting only really works when there is hardly any traffic.
Plus of course there is no transponder requirement in Class G anyway, so remember that the other aircraft may not have even had one, let alone had one correctly selected to ALT. Maybe there was another one out there that ATC couldn't see!
Of course use everything available to you. If you have a transponder, use it, but remember that not everyone may have one fitted or turned on. Even if they do, don't expect ATC to give you traffic on other VFR aircraft all the time, because they won't!
Keep your eyes open!!
Recently someone in a Cessna flew outbound right over a VFR inbound reporting point, at the inbound reporting altitude, while we were inbound at the same level. It was a bit hazy so we had nav lights, strobes and landing light all on, and the aircraft is a highly visible colour too. Bright colour, flashing lights, but the other pilot didn't see us ahead. Waggled wings. Still the other guy didn't see, so we took evasive action, and still the Cessna flew on, completely oblivious to our presence.