Detail is relatively poor, main roads, main towns, etc, certainly not for trail-road seekers. But then again, it's a good compromize between size and detail. Takes around 150-190MB whole World into your GPS (in comparison: US of America full map is 4-8GB for example, so you know how much detail there is in 200MB covering the whole World).
Did I mention Estonian town names are a humor in World map v4?
Anyways, hopefully it keeps me "mildly" on track for my future travels - just don't have enough £££ to spend for each third-world country I'm visiting... and I'd prefer to have smaller roads + trail roads marked everywhere.
So I'll always keep my proper paper detailed maps and compass with me tho.
My new Zumo550 seems to have this already loaded as a base map. e.g. I can zoom in to New Zealand or Seth Effrica. Unless, of course, they've vastly improved "World Map" from my old version.