Thanks to a controversial member at neoGaf forums (at http://www.neogaf.com/forum/showthread.php?t=142786)
I found this little gem for PSP and DS):

Puzzle Quest: Challenge of the Warlords for PSP Review - PSP Puzzle Quest: Challenge of the Warlords Review

I really need to recommend to you, guys, Puzzle Quest. For either the PSP or DS, doesn't matter. Both versions are great.
The highlights are (PSP version):

1. (1) Excellent pace. The perfect handheld game and an example of how PSP niche game should fare
2. (2) Nostalgic, "Might& Magic" overworld map system
   
3. (3) Addictive puzzle-based combat system which evolves into a fully fledged strategy game (not without its share of exploits)
   
4. (4) Outstanding soundtrack and great sound effects
   
5. (5) very good artwork (as usual, looks astonishing in the PSP screen). Interestingly, with a certainly anime-ish influence, with contrasts with its deep routes in the traditional 90's PC WRPG foundations
   
   

The best way to describe this game is as an old school PC WRPG (it reminds me of the oldest Might and Magic games) with a unique combat system based on a puzzle game not much unlike bejeweled/zoo keeper. The nice thing about the mechanics is the fact that achieved puzzle blocks generates you either gold, mana, damage or experience. Mana is in turn used to cast spells which may affect the board or the stats of the players.

While the puzzle part, at the beginning of the game, suffers from being a little bit luck-based, soon after you start level grinding, you get offered with a wide selection of tools to change the combat from a skill/luck based showdown to a clever and addicting strategy game where a war of attrition is placed over the adversary, and many trade-offs need to be evaluated beyond the obvious implications of every move.

Another very nice thing about the game is the puzzle variations that are involved with the different aspects of the game. Some
examples:

1. (*) You can capture creatures you have already beaten a certain number of times. This is done by a puzzle challenge where you have to eliminate all the block pieces on the board with a certain number of moves
2. (*) You can train mounts by playing a version of the puzzle with time limits. This has obvious parallelism with fast check matches as it changes radically the way you play the game
3. (*) You can learn spell from captured creatures by being able to create a wish-list of blocks from a static board
4. (*) You can create new items (which nice bonus) by being able to match together special symbols on the board
   
   

Summarizing up, I can understand that this is a niche game that fills some particular tastes. Nevertheless, I firmly believe that its scope widely fits the needs for what a good portable title should be. Slow paced mechanics with fantasy settings and a outstanding level of strategy gameplay have been some of the ingredients of the receipt for many of the best handheld titles I have ever played (like IS products: Advance Wars and Fire Emblem)

It's ironic that this is first real instance of such concept on PSP (as MGA was an interesting spin of the concept, yet flawed,
and Field Commander was a terrible let down). Maybe, recently, Devil Summoners was close, too. And I really believe it's a luxury to have such value regarding artwork, soundtrack and presentation for what it's basically a low budget handheld game.