A lot of people saw Gameboy Advance and thought it had the best graphics ever. It has good music for a handheld, I'll admit to that much. People were also tricked into thinking that Gameboy Advance games had the deepest gameplay for a handheld because of its larger memory. Guess what- they're wrong. The Wonderswan systems, made by Bandai, are among the best systems in the pocket gaming universe (discounting pocket games from other dimensions and galaxies). Strategy fans though Advance Wars was great. They should try SD Gundam G-Generation Gather Beat 2 and Monoeye Gundams. They thought that Golden Sun was cool. They should try Gensoumaden Saiyuuki: Retribution. There are tons of other games that are good, as well. Oh yes, and Square remade Final Fantasies I-IV and Final Fantasy Legend for WSC, if you're interested. And the newest Gundam series, Gundam SEED, was made into a Wonderswan Crystal game, instead of Gameboy Advance. The only real disadvantage that the Wonderswan systems have is that the sound isn't always as good.
If you're interested in buying, purchase a Wonderswan Crystal off of eBay. Just thought that all you GBA followers should hear about this...
Wonderswan is weaker than the GBA. GBA has more graphical power too. There is always a game on GBA that looks better than any game on WS.
Digimon Battle Spirits was the only port from WSC to GBA. I really wished they released FF1-2 to GBA.
WSC never recieved FF3. The bad part of the system is that it is dependant on you knowing Japanese. Many of the games are RPGs or Simulation games that are heavy in text. Or at least, from the ones that I could see.
If you're interested in portables, check out the Korean only GamePark 32.