It is surprisingly impressive. I would expect something of this caliber from a higher budget American studio (everyone knows America has the best technically inclined staff at their disposal).
When I watched the first episode I was in awe, this show was much better then next to anything I'd expect from Australia. It has so many things you just wouldn't expect from an Aussie show, and it's on so many more levels. The technical skills and creativity are much better then most other shows on the same budget.
I went to the 24 Hour Film making festival of 2008, and I was surprised to find the lead actress of the first episode there (Aurora). The directors make the actors look great.
It is better then most other cop shows. The stories are a lot more complex and things are done more interestingly. It's not just "find the evidence, yell at the killer", it is visually entertaining and more intellectual. They characters aren't just run off the mill killers, there are large stories behind them all.
It obviously doesn't have the budget of CSI, but it is certainly more interesting (I mean, who wants to watch a monotonous guy wearing sunglasses indoors?). It's more like Law and Order, but even then, the technical skills are better and it makes it visually more entertaining.
I do have to admit, watching it for the second time around it's not as shocking as the first time around, but lightening doesn't strike in the same place twice. I am glad it has been brought back for an encore series. I'll finally get to watch the episodes I missed!