From one Suiko fan to another, the only games I truly enjoyed on my PSP was Jeanne D' Arc and tales of Eternia. So I say bump them up to priority wish list if you want an RPG fix. Tales can be considered a side scroller beat em up, just keep fighting random battles. =P Final Fantasy Tactics was a disappointment considering how much I loved it when I was a kid. Partly because I hate the new translation of Ye Old English in the Lion's war. Other than that I just used my PSP as an mp3 player. It's retired now though.
Just in case you're interesed in review scores.
Jeanne D'arc -Best and worst reviews.
100
The Onion (A.V. Club)
Folks who traded in their PSPs for lack of awesome games should be feeling substantial remorse right about now.

100
GameShark
Jeanne D'Arc manages to deliver on all fronts, from the presentation to the fast paced and streamlined open-ended battles and skill binding mechanics. Everything in this game is polished, pretty, highly functional and fun. At the end of the day it's hard for me to complain about anything in this game.

96
Digital Entertainment News
Immediately becomes the best reason to own a PSP in ages. MUST… HAVE!

95
Game Chronicles
Jeanne d’Arc is the best tactical RPG that I have played in a long time. The amount of skill customization and various character types with their own weapon types and skills is amazing as is the sheer level of detail in ever facet of the presentation.

95
TotalPlayStation
Jeanne d'Arc does nearly everything perfectly, and I know I keep harping on this, but it's just a stellar first effort for Level-5. If your PSP has been collecting dust since, say, Crush, break out the dust mop and grab this game.

93
AtomicGamer
Jeanne D'Arc is one of the best games to be released on Sony's portable system to date.

92
Cheat Code Central
I was thoroughly enraptured by Jeanne D'Arc. It's a sweeping epic that has both the mechanics and visuals to make it a must-play title.

80
NTSC-uk
There’s no doubt that coming to this game from something such as Final Fantasy Tactics or Disgaea will prove to be too easy a ride for those experienced with the genre, but for anyone looking for a more portable Strategy-RPG, with a wonderful story to tell, Jeanne d’Arc will be a perfect fit.

77
Electronic Gaming Monthly
While it certainly doesn't reinvent the genre, Jeanne's gameplay wisely blends aspects from other successful tactical-RPGs. [Sept 2007, p.97]
70
EuroGamer
The storyline, while clearly bonkers, makes a refreshing change to the standard RPG fare, if only because it draws at least superficially, on historical characters and events.

Tales of Eternia -
98
GameBrink
The absolute best portable rpg that exists for any handheld system to date. [JPN Import]

90
PALGN
Simply, Tales of Eternia is one of the best games you can get for the PSP. It breaks the RPG drought and is one of the best handheld RPG’s since "Golden Sun."

90
AceGamez
It's charming, well presented, deep, involving and infinitely rewarding.

90
Deeko
There isn't a modicum of doubt in my mind that this is the best RPG on the PSP.

70
Official Playstation 2 Magazine UK
As old-skool as RPGs get, but in a good way. An enjoyable journey gobbler. [Christmas 2005, p.110]
60
Sydney Morning Herald
The combat is quirky and original, but it's a system that RPG stalwarts may dislike for its dependence on reflexes over character statistics. It also takes some getting used to, so be prepared to stumble through the game for a while before you find your feet.