A co-worker from another office up in this neck of the woods for business was so kind as to run a Pathfinder one-shot over the last two nights. While I was unable to make it on Monday, I partook yesterday, running a dwarven cleric. Things were... different. Everyone else was very new to D&D/RPGs, so we had a pair of half-elf melee sorcerers, an elven paladin, and an elven archer druid. The party became split regularly, we only formed a good solid defensive line once, folks took lots of damage, and it was a good thing we had a cleric ;)
But man, in 1st-level PF, orisons at will are a huge change from 3.5. Neither of our sorcs had a crossbow, because of infinite acid splash availability (despite my argument regarding expected damage on a d8 non-touch ranged vs a d3 on ranged touch, range considerations, and the situational usefulness of each). Felt very 4e in that regard. Likewise, while getting a giant pile of domain power uses per day was handy, it was also very weird to be like "Nah, rather than switching weapons to my crossbow, I'm just gonna shoot acid from my hands. Totally normal dwarf cleric thing." This caused the magic level to feel much higher.
The turning changes (to channel) were sort of interesting, but in practice it ended up being used as mass healing (since we only met one group of skeletons, and that was the one time we formed up the shield wall and held formation alright). On the one hand, I don't like that it reinforced the primary utility of the cleric as being in the healing department. On the other hand, so often in 3.x, your turnings per day were irrelevant, and it did save some spell slots for bless (as well as saving some lives). So I'm on the fence about that in play.
Finally, coming from ACKS - holy crap high ability scores and many many numbers on character sheet. And no henchmen to take the blows! (though I guess this was OK because I had like 3x as many HP as your average ACKS Clr1...)
Anyway, very different. DM was pretty good, made a point of throwing us some difficult fights (we should've TPK'd on the last one, but he had some atrocious luck rolled in the open) and did not pull punches that I could tell, so that was a nice change from most of the 3.x games I'd played in.
In any case, it was a good time, but I think I will be sticking with ACKS as my weapon of choice.