The only difference between the 580 and 570 is the 580 can be updated using WiFi rather than having to connect to Garmin Express via computer.
I got one a few months back and have no complaints with it. Would recommend shopping around though, I found a seller on eBay selling them for around £280 and used a 20 percent off voucher I had so got it for about £225. At that price it’s not much more than a decent car nav, but at the £400 rrp it’s down to you if you can justify it.
The WiFi updates are handy for me as the Garmin updater only works on Windows or Mac and I run Linux at home, also means it’s easy to update while away too.