I'd give it a 5 and I think it's usable, expecting most folks to recognize it from "LOTR". Looks like it's mainly in use as a feminine name, which I understand given that it's a place name (a kingdom, not a city, if I recall correctly) but, sound-wise I think it feels more masculine.
I prefer Ronan to Rohan (for a boy). I don't like Rowan on a girl which lately seems to equate to not liking Rowan.
I stress the first syllable "RO-han" and don't think it likely most folks would intuitively stress the last syllable. If you want it pronounced that way, you likely do a lot of correcting. Don't know where an "r" sound would come from unless in a region where there's a strong accent, kind of like the way the British tend to pronounce things that end in "a" as if they end in "er".
This message was edited 1/20/2014, 11:21 AM