Anyone used a Seagull Right-angle viewfinder?

[Bend The Light]

I just bought one on ebay...not sure of the model but the guy had it on a 350d, and since I have a 400d which is identical in the viewfinder department, I figured it would be fine.
I paid £5 for it which I think is reasonable...they are priced £50 and up when i searched t'interwebs...

Anyone used one? Any good? I have issues sometimes when shooting macro, spiders and the sort...they're never easy to get and having no live view makes it harder.

Any thoughts?