When I intentionally went back to play all the PS1 RPGs I missed (I grew up in a Nintendo family), this was the first one I played. Put over 40 hours into it easy and it never felt stale.
I love this games leveling up system too, it's the kind of thing like SoM where you level up magic and skills the more you use them!!
I thought only MoC was Vita. The ones before that were PSP? I have Oath In Felghana, which is definitely PSP. Haven't gotten to it yet though
I really like the Ar Tonelico series and Ar Nosurge is a prequel to that series. I personally didn't like Ar Nosurge, I thought it was all over the place, but it's got great reviews everywhere. I just wanted to to be more like the Tonelico series. I am excited to play Ciel Nosurge though since that sounds much more in line with the Tonelico series. Anyway, keep a look out for these in the future.