I have seen a few questions raised and thought I would share my recent trip and how the alliance worked outside Oz.
Flying Air New Zealand, wasn't all that difficult getting into the Koru Lounges, one issue was that they had me as silver on my Air NZ ticket, upon showing Platinum card it was all good, that's obviously an error in communication from Velocity to Air NZ they said.
Flying internally with Delta was different though.. I actually did the status match challenge to get Gold medallion, I must say they look after their Frequent Flyers very well. Only thing with that for them is they don't get lounge access with Gold over there, I was able to get lounge access to all Delta lounges but they had to look and search a few times, in NY they weren't going to let us in, they don't know of the alliance it seems, after getting them to look up the Delta website they saw I was allowed in and then it was all good. The one big benefit I found is that Delta and Air NZ have an agreement with Luggage, we travelled back to Aus on a Delta ticket then an Air NZ ticket and they were able to send luggage all the way though, only one person informed us of this and it made life easy as Delta are much better with more bags than Air NZ so I think it ended up saving us money too.
As far as getting a Status match, it was well worth it, upgraded on most legs, they have abgreat system that means Business is always full on pretty much every flight, there is a standby list and in order of status, then flight delays and finally ticket price, as a matched Gold, was basically at the top each time as well as my wife with no status, I think Virgin Aus should look at doing something like this
On top of that you get a goog luggage allowance as Delta you pay for this separate, being gold allowed us to check all luggage without issue.
Overall, had no issues with lounge access as some others have said perviously, they needed a nudge on occasions and I think the Delta alliance will be great going on the few flights we did with them.
Flying Air New Zealand, wasn't all that difficult getting into the Koru Lounges, one issue was that they had me as silver on my Air NZ ticket, upon showing Platinum card it was all good, that's obviously an error in communication from Velocity to Air NZ they said.
Flying internally with Delta was different though.. I actually did the status match challenge to get Gold medallion, I must say they look after their Frequent Flyers very well. Only thing with that for them is they don't get lounge access with Gold over there, I was able to get lounge access to all Delta lounges but they had to look and search a few times, in NY they weren't going to let us in, they don't know of the alliance it seems, after getting them to look up the Delta website they saw I was allowed in and then it was all good. The one big benefit I found is that Delta and Air NZ have an agreement with Luggage, we travelled back to Aus on a Delta ticket then an Air NZ ticket and they were able to send luggage all the way though, only one person informed us of this and it made life easy as Delta are much better with more bags than Air NZ so I think it ended up saving us money too.
As far as getting a Status match, it was well worth it, upgraded on most legs, they have abgreat system that means Business is always full on pretty much every flight, there is a standby list and in order of status, then flight delays and finally ticket price, as a matched Gold, was basically at the top each time as well as my wife with no status, I think Virgin Aus should look at doing something like this

Overall, had no issues with lounge access as some others have said perviously, they needed a nudge on occasions and I think the Delta alliance will be great going on the few flights we did with them.