First of all, Judgement Silversword isn't for the GBA, it's for Wonderswan Color/Crystal. There are videos at http://members2.jcom.home.ne.jp/jss2/index.htm. It plays like a dream, manicness at its best. Going price is somewhere on the $150-200 range, assuming you can even locate a copy. And there's even a high-score thread for it...
No matter how good a game is, somebody will always hate it. No matter how bad a game is, somebody will always love it.
Ah, here's the ingenious part - you turn the WSC on its "side", so to speak and play with a vertical screen. See the picture at http://www.play-asia.com/paOS-13-80-1-70-1qx.html? There are three sets of buttons for controlling (upper left, lower left and lower right on that pic), so it's easy to just switch when playing vertical games.
So all you who thought the PSP was cool for allowing you to do this with Galaga - it's been done better before.
No matter how good a game is, somebody will always hate it. No matter how bad a game is, somebody will always love it.