I realise I'm probably on a loser here, but I have 19 of these things I'm using as fermenters presently. All code 7, no less, which some quarters would pass off as the greatest crime possible.
For every argument against them, there's a counter to read on the net.
It's all a matter of what you can afford and what is available. Glass doesn't do either for me.
In 12 months I certainly haven't detected any off-flavours in my brews. There are a couple of things I wouldn't do though; put boiling water near them or use them for high alcohol (above 20%) storage/brewing. I'm getting a still underway and these things won't figure there at all other then as an after primary fermenter. I find them great for secondary and aging, cleaning's a breeze.
I doubt if I'm on my pat malone here, others just aren't putting up their hand.