It's not a remake, it's a port with additional features like CG cinematics instead of the crappy, boring sprite based ones from the original. There's also some remixed songs; other than that, it's pretty much the same game.
Still, Valkyrie Profile was a limited release game back in Square's "ORIGINAL GAMES" hayday; you know, when they made GOLD games like Einhander, Brave Fencer Mushashi, Vagrant Story, and Parasite Eve. This was back when Square was good; before they decided to WHORE OUT Final Fantasy 7 and throw gobs of money at tri-ace to produce their same old garbage like Star Ocean 3, Radiata Stories, Rogue Galaxies, and TRUSTY BELL: LETS PISS ON CHOPIN'S GRAVE.
Anyways, Valkyrie was a game that broke almost every rpg cliche; for one, you played as a fucking GOD and if you didn't start on hard mode you started out at level 25 or so. You could fly around the planet and pretty much visit every location from the beginning (although you had a hidden time limit of things you could do in a single "chapter" of the story so it wasn't completely open ended). The game was a sidescrolling rpg with lucious 3D backgrounds and GORGEOUS 2D sprites (we're talking massive Guilty Gear style sprites here). The battle system was fast paced, well balanced, and incredibly flashy and the combination of rpg elements with platform puzzle solving in dungeons was ingenous.
Despite being a sidescrolling rpg, the game was about 40 hours long and contained an incredible amount of storyline and written dialog. Thankfully, UMD's hold 4x more storage than cd's so they completely redid the cinemas in CG and added in voice acting so the story isn't told in such a dull way.
Seriously, BUY THIS GAME. Valkyrie Profile was one of Square's TOP GAMES but Square didn't put a lot of advertising behind it because it wasn't a LOL FINAL FANTASY game. You can find the ps1 version for an insane price on the internet (usually $80-100 for the COMPLETE package) so nab the PSP version while you can because I doubt it'll be whored around like Final Fantasy 7. You won't be disappointed; it was one of Square's best original games; third in line with Xenogears and Vagrant Story in my opinion.