I can give you a decent synopsis of what Druid is like, while I have not played a Shaman I know more or less that if you enjoy your Shaman now, you will enjoy it in MoP.
Resto Druid: Really love healing as a Resto Druid, it is one of the more fluid healing classes in the game (not clunky like a Disc Priest) HoTs are quite strong, they will never be the best tank healers but they will always have great throughput, they are especially strong in fights with heavy AoE damage, but lesser in fights where boss mechanics give heavy mana regen (since we don't have an ability similar to Holy Radiance) but overall I really enjoy healing, I think they have made it slightly better in MoP and with Symbiosis, I think they will have PvP viability again since they already possess quite strong CC with limited survivability which is now going to be increased greatly with the new talent system and Symbiosis (which is a bit OP right now)
Feral Druid: It will be good for PvP, will be rare to see one in a 10 man, might have a slot or two in a raid in 25 man, not too many notable changes with the exception of Symbiosis
Balance Druid: In Beta right now, I really, really dislike Balance Druids, I think their rotation is horrible and really uninteresting, and it will most likely stay that way, I think they will become weaker for PvP since their DoTs are ticking for a fraction of what they do now (and they are getting rid of Insect Swarm as well)
Guardian: I think it will become a premier tank to have in your raid group, lots of CDs & Symbiosis also gives useful tank CDs for Druid, ability to switch to kitty mid fight is really good utility as well
Overall: DPS kind of sucks, healing should be pretty good, tank spec is quite good, if you really enjoy Shaman I would stay stick to it, although Druids are quite fun as well if you play the right spec