Let's look at the negatives first, before becoming starry eyed:
1. Although it has plenty of infrastructure and is a rezoned beachside suburb with development opportunities, Frankston is not a high-status location. It has its fair share of social problems. Thankfully, the bogans and ferals seem to be moving inland, driven away by increasing rents.
2. Frankston is one hour from Melbourne by train - not great for commuters but fine if you work locally, as most residents do. The new highways and roads don't make much of a difference, in my opinion.
3. Crime in Frankston is around that of inner-city Melbourne. There are plenty of colourful stories about how ambulance workers in Frankston need police escorts etc. These, in my opinion, are exaggerated.
4. Paying too much for any property in Frankston, regardless of redevelopable opportunities, is not wise. Many people, including a few on this forum, have made this mistake. Regardless of what agents may say, the rewards are to be had in choosing cheap old houses on large blocks. Forget the kitchens and bathrooms - local yields are rarely more than 4% anyway.
Why do I think Frankston is such good value?
Basically there is only one reason: because the low-end of Frankston has become incredibly mispriced to the point that its pretty hard not to make a capital gain.
The median is around $360,000. However, you can easily get an old house on a dual or triple occ development site for as little as $300,000. The sort of property where you can retain the old house and build in the rear in a few years, when you are ready.
My personal estimation: if you buy in the lowest decile of house prices, you will see IMHO 20% capital gain in the next 12-18 months if you buy carefully.. Pay too much (as many did in the last boom) and you won't see that sort of gain. Again, be warned, there is no point paying more than the LQ median as there are plenty of redevelopable sites within this parameter.
Again, Frankston is not for everybody. In my opinion, the positives exceed the negatives. If one buys intelligently, making 20% in the next year is like shooting fish in a barrel.
Disclosure: I recently sold my WA portfolio, which I acquired in the 1990s, and put the bulk of my net worth into Frankston.