Solo will always be a challenge here, but not impossible if you have the patience.
There are multiple people in Ding (leveling guild) who are doing their solo toon thing and still making progress. I know of at least a couple who are pushing level 60/AAing at the moment.
Definitely more challenging for a melee than a caster, there will be times you don't find a group and solo options might not be worth the trouble.
I think if you make the grind into the 60s it's likely to offer a lot more promise since many trio's are happy to bring in another useful player for xp bonus purposes, and a competently single boxed character can be a treat.
The server is definitely top heavy, but the mid levels aren't barren by any means, people are just typically focused on the hotzones for those levels (Mistmoore, Katta).
If you decide to give it a shot, join Ding asap, at the very least you'll find some folks willing to give you a leg up. I'm always keeping an eye out for solo toons that could benefit from the extra help.