This game takes me about 10 hours level grinding to 99. In a way, that's short to me, but it's fun the whole way, just like how Ys games tend to be. They may not be the longest games(not even the newer ones) but they're fun thru the whole experience.
As for more Legend of Heroes games, there are more, but they aren't part of the Dragon Slayer series. Legend of Heroes 3-5 are the Gagharv Trilogy. You can get all three(renumbered so that they are LOH 1-3) on PSP, but....the translation is horrible, & Bandai apparently messed around with the original battle system & made it kinda boring. I still enjoy them regardless of this, but I can tell they were originally MUCH better games.
There's also Legend of Heroes 6, known over here as Trails in the Sky for PSP. That game, is near perfect. It's VERY well written & VERY well translated, & it was originally ported to the PSP by Falcom themselves, rather then Bandai, so it's just really well done over all. Only problem is, the 2nd game in the Trails trilogy is massive, so it's taking forever & a day to translate. Plus, when Falcom originally ported Trails 2 to the PSP, it was on 2 UMD's, so that when you get to near the end of the game, you have to switch back to the first UMD(the game is huge), & they haven't been able to get it up on PSN because of this, which means less sales(especially for those with a Vita would want to play PSP games). So, Xseed is basically just waiting for Falcom to have some spare time(months perhaps?) to re-code it so it can be put up on PSN. I'm still keeping the faith that somehow it will be released for PSP eventually. Even if it's in limited number of UMD's. OR, there's been the talk of possibly putting it on Steam, but, I'd prefer PSP myself.