Well I hit lvl 20 as a monk now, and I have found that to get exp, many of the green mobs are a low risk kill solo , but a blue mob can get you lower than 50% health easy, so making it quite risky if you get an add , as for white mobs you get well close to death, So yes solo seems to be very slow way to get exp but on the upside there is lots you can solo in Antonica anyway, just dont expect fast exp thats all lol
I would just like to add the main reason for my buying the game was so i could solo easy and get decent exp at the same time if i wanted to, but as you all have pointed out this does not seem to be the case
just my 2cents worth of ramblings lol