Focus on this.
The more I think about how to make a melee-focused druid, the more I think suckage. Your AC is going to be in the auto-hit/crit-me levels, unless you skip spell casting altogether...and even then I'm not sure. I would love for someone to prove me wrong.
Sounds right. Even in 3E, where druids were CoDly, their AC kinda sucked. And I mean full AC, with the natural armor (unless you took a form with hugen at armor at the expense of your offense, I guess). The expense of wilding clasps and beastskin armor adds up. Thier touch AC was universally abysmal unless iin a graceful flying form meant for stealthy spellcasting mroe than combat.
In PF, the better combat sizes actually
decrease your natural dexterity. You get more nat armor than you lose from dex, but the touch AC definitely suffers. And with difficulty getting armor to apply while wildshaped (and shield, if your DM is wisely using RAI instead of RAW, since RAW a shield bonus sticks while wildshaped), never mind that druids have crap proficiencies anyway...I'll bet their AC is probably pretty terrible for a melee character.
And druids do get level 9 spells, but they also have probably the worst overall spell list (I'm sure some will disagree with me...). And since ultimately casting is the most powerful thing, that's notable. Not saying druids are a bad class in PF. They're solidly "middle tier" or maybe even the lower end of high tier with the spellcasting used well. Perfectly viable class to play, still loads of flavor and cool abilities. They're just not as powerful as the other 3 prime casters anymore, IMO, and I find it silly to ask if druids are overpowered in PF before/without inquiring about the cleric, sorc, and wizard.