Okay, I played FF1 and FF2 Dawn of Souls both for about 15 minutes, and here's what I can tell.

FF1 seems a lot like the Easy version in the PSX at least with the way how you'll gain levels super quickly and how everything is cheaper. You also have some (very lousy, though) equipment at the beginning of the game rather than having to start the game with no equipment at all. The magic uses MPs this time. Cure takes 3 MP, Fire and Bolt take 5 MP. Your mages have 10 MP in the beginning. Wanna know how quickly you level up here? I started to march to the Castle of Fiends. I fought 3 battles against Goblins. Level-up. I defeated Garland. Level-up. Already at level 3. o_O You can also save anywhere, even in dungeons. There's also no chance of enabling the Ineffective feature. :/ Meh, I hope the game gets challenging later or this will be a total cakewalk. What I like is that the loading times are pretty much nothing. This game plays even faster than in the PSX version! BTW You can choose to auto-name your characters. It seems every character has their own set of random names. White Mage had mostly female names (though also a few male ones), Monk had mostly male names (I can't actually remember female names for monks) and other classes had both.

FF2's battle system seems a lot better so far. Every action takes faster in battles and menus, which is a good thing. What I like is that whenever someone speaks, that character's face and expression shows up in a textbox along with the dialogue, similar to Chrono Cross and Kingdom Hearts: Chain of Memories. A very nice addition. Just like in FF1 DoS, you can save anywhere, even in towns, and I assume dungeons too. The weapons and spells level up a LOT faster this time. I got my weapons to level 2 by attacking with them twice, and to level 3 by attacking with them a bit more than 5 times. I also got my Cure spell to level 2 by casting it about 5 times. Very nice. This is how it always should have been, weapons and spells leveling up faster in the beginning, and later requiring more work to level up.

My first impressions of the GBA version was very good. Even the sound and music quality seemed pretty good. Not the quality of PSX version, but it's still high quality, and each sound and instrument is clear and distinguishable.