Are Perth's latest sections of bike path any good? 

I'll answer that clickbaity title here - yes, they are. They are very good indeed.
They're wide, they're smooth, they're well sign posted and the drains aren't in the middle of the path and there are very few service manholes and the tunnels are generous and the only thing I didn't check was the lighting.
The latest section of path going north alongside the freeway also has three bike counters on it. This got me thinking about the Heath St bike path debacle and whether the outcome would have been any different if we had a few months of hard data on bike movements (both on the path and on the street) vs vehicle movements and vehicle speeds.
I doubt it - but it's worth thinking about for future bike infrastructure in NSW. Bike counters should be included in the project scope to ensure data is collected from Day One.