I guess I need to step in and drop a few lines in favor of the druid. Considering my shammy is pretty low level (around 6, I dont play him much) I cant comment reliably on that class, I am playing a druid as my main adn will do so for release.
I dont know much about a shaman's arsenal of spells but from what I heared (and that was before the revamp either) they start to be real fun at levels 15+ but then they rock. They are good healers, have great buffs and the class defining quests add alot of difference.
Yet I love playing the druid class, it has been much fun ever since. When it comes to soling I can take light blue 3dots and green 4dots without any hassle. If you go against meele type mobs (no caster, no ranged attacks) you can kill a mob without beeing hit once if you are careful. Druids kite pretty well in Vanguard as they recieve a 40sec snare, combined with the movement buffs from SoW and Wolfform you are always faster than your enemy. After youve snared a mob you can move backwards and cast and still be as fast the the mob.
Still, soloing as a druid requires skill and a cool head at times. The downside to kiting is that you need room to do that. As you are running around, circeling the mobs you may get an add here and there which just adds to the fun imo
Yet if you go against simple 2 dot mobs there isnt much of a difference I guess. Before the recent changes to the mobs HP I could chain pull yellow 2dots without even worrieng about my mana. After the changes I have to rest after each 3 4 kills. In todays patch they increased the experience gained from all cons above 2dot so this might have turn the table in favor of the druid either but I havent been able to test yet as the servers are down still.
As always I'd say test both classes and take the one that you connect more with. Soloing should be possible with both of them, its all about the risks you are willing to take. Grouping on the other hand may be different but to be honest I havent had any troubles getting in a group so far. While druids may compete with rangers, bards and sorcs for DPS, as a shammy you'd have to compete with BMGs and CLRs for the healer spot. And if you'd ask me Id say that Id rather take a tank, healer and 3 misc DPS classes over having 2 3 healers in a generic exp group.
My 2cp :P