The GBA version is too ridiculously easy, coupled with the insane encounter rate (a battle every 2-3 squares) makes it rather frustrating, even though it's so simple.
I've yet to complete the Soul of Chaos dungeons (because of the above-mentioned encounter rate), but I plan to try and complete them on my current playthrough.

I didn't realise the PS version of FF1 was worth trying out...II, Chronicles and Anthology were such abortions I assumed 1 would be the same.