Yeah, Ys 3 on PS2, from what I recall, has alot of the scrolling removed, so that it's more comprised of rooms, like Zelda I guess, rather the huge rooms that scroll. I do recall some area's having scrolling, but like BT said, it might be just the bosses. Overall though, it's fairly decent, & the best of Taito's Ys efforts I think.
Also, I totally forgot about the PS2 Ys 5. I have it, but haven't beaten it yet. It's supposed to be a much better effort then the PS2 Ys 4. I have no idea how closely the plot follows the SNES game. I didn't know about Ys 5 on cell phones though, I assume it's a direct port of the SNES game?
Also, there is a disc I have, that I think came with Ys 6 PC (or maybe it was Ys Complete?), that has 1-5 emulated on it for PC. I forget which versions 1-3 are(PC-88 perhaps?), but 4 is the SNES MotS, & 5 is ofcoarse the SNES game(though, I don't recall if it's the original, or expert).
Oh, & I just got Ys vs Sora no Kiseki Alternative Saga off ebay for dirt cheap. Mainly got it, cuz I'm assuming that if it ever get's released in the US, it'll probably be digital only, & I like to have the complete package. It actually contains spoilers to the 2nd & 3rd Trails in the Sky games(which haven't been released yet), so it could be awhile if it ever see's a release out here. Anyways, it seems cool. I believe some call it an Action RPG, but....I'd deffinitly say it is indeed a battle/fighting type of game, with exp. points & alot of story.