Don't know anything much about it, but I have got one!
"Hamburg Ring" refers to the style of grinding and isn't a trade mark. These Ring razors tend to be wide and reasonably robust; there was some discussion and speculation on the subject recently in this thread. My Electric Razor shaves very nicely indeed thank you, so yours should be worth restoring for use. As regards value, that's entirely in the eye of the beholder - it was a tenner and a half hour of honing well spent in my case.
I found one of these at a car boot a few weeks back, it was a little rusty. I sold it on to Professor Blighty and I think he's looking to restore it, so maybe PM him and compare notes. I'll try and find the thread where I discussed it.
Edit: It's not the same make but it's remarkably similar looking:
http://www.theshavingroom.co.uk/forum/showthread.php?tid=168&highlight=hamburg