Did the firmware update to 59.00.449 this morning (last European version before they blocked it) and it was quite easy. Just time consuming. I'd give yourself 2 hours from prepping the USB to it finishing. Followed the video in the Mazda3Revolution thread and it was all pretty straight forward.
It seemed to fix the not connecting to my iPhone's mobile hotspot problem. Although I have no idea why I'd ever do it.
I then installed the tweak to allow further tweaks installations if I choose to update the FW higher, and then installed some mods. The speedo is ok, and turning off the beeps and warning screen was useful, I also installed Android Auto for the hell of it, but obviously cannot use it being an iPhone user.
Despite doing all the above, because I'm a bit geeky, I'd probably say it's not actually worth bothering with, unless you have a bug that's annoying you in the Infotainment system, or have an Android and want Android Auto. I might order a cheap handset of Amazon tonight to arrive tomorrow and have a play, and just send the phone back under distance selling regs or whatever it's called these days. Or if it's cool, I'll keep it.