I otherwise agree with these criticisms, but a few notes here:
Can't escape dungeons unless spend 10% of money: The wind temple entrace is flooded with water so if you enter with sana and then, while exploring the dungeons, sana is defeated by enemies (something very common for a character with low HP) then you are trapped. You can't go forward because sana ability is needed and you can't go back because...sana ability is needed to escape. Which means that need to spend 10% of money for escape.
Just commit suicide by kamikaze and restart the current room for absolutely free. There are a handful of situations where this can't be done (no holes in the ground, f'rex, or your team is already seriously wounded/down one when you enter anyway), but the point of subtracting 10% for an escape is to offset the free retry-room you get.
I'm not too happy with Recall Lamps only appearing when you get to the catacombs and Teleportation being one of the very last things Sana learns, but still, many other ARPGs just outright subtract 10% $ from you *upon death* if you don't have a resurrecting item. You're getting a pretty generous deal here, considering that for some reason fewer people can play this sort of game these days.
Edit and PS: It's actually not possible to be trapped between 2 water bodies in the Wind Temple. Sana would not have learnt Mermaid Cloak by then (so it is impossible for Arche to follow Sana into a position where she cannot make it back on her own). And, switches do not reset: if you pulled the entrance switch it will remain pulled; the water level will not be reset.
You should be able to exit the dungeon safely with Arche if Sana gets KO'd halfway. I lost Sana there many times, I should know. <_<
Expensive items: basically any armor that may make exploring a little easier cost 500 coins+.
Funnily enough, I agree with this - because every time I buy gear from the shops, up until the last 3 days, I find *that very same item* whilst exploring the dungeon, then hit myself for deciding to buy it because I just wasted half the price of the item. >.>
Harpies and Bees are rather painful to encounter since they either put you to sleep or confuse Arche into beating up her friends. Receiving anti-status items in the appropriate areas as enemy drops would be nice.
To be honest the only way to deal with status in this game seems to be pumping up MDef. Even the "Earrings" which Colm and the boys claim to protect against Confusion (and you'll get one for free) seem to just increase MDef.
3) Save/Load extra dungeons - I would like to have the ability to replay the extra dungeon(s) that are available from the load menu, just in case I missed something.
I think the bonus demo dungeon isn't in the full game...
Characters AI is not smart: This is specially annoying with sana, that only uses shield and runs around the map instead of use her ice magic.
You'll need to micromanage her (and Stella) a little if you want her not to use certain spells. Turn the abilities off in the abilities menu, and AI Sana won't use them until you turn them back on (bad thing is, you can't either). When you get more than 9 spells you'll start seeing the entire point of disabling spells, since they all can't fit into the same "spellbook", and you'd want to turn off the L1 versions of any L2 spells you get.
Now, the fact that they can't jump on moving platforms with you, I agree.
Note: AI Sana will NOT cast Mermaid at all, so you can safely keep it active.