Lunar Legend is a great RPG for beginners.
The gameplay is very simplified, and extremely easy to get into. If you have played a turn based RPG before you will be kicking butt right from the start, but if you have never played an RPG before, you can still get into the game very quickly.
The sound quality in this game is fairly decent, about what you'd expect from the GBA. However, the music is recycled over and over again, and after about 10 hours of game time, you'll be turning the volume all the way off.
The story is extremely simplified compared to the game it was based on, but some of the main elements remain, and if you've never played a Lunar game before, you will be able to follow it rather easily. It's you're classic "save the world" type story that is repeated in countless RPGs, so some may find it boring, but again, if you like RPGs, you'll still like the story.
The graphics in this game are on about the level you are used to seeing from the GBA, with nothing really special, but nothing truely awful either. Expect the same kind of background recycling that is famous from 16 bit era RPGs.
The game seems overly short, but maybe it's just the constraints of the GBA cartridge showing itself. Expect to beat the game in 25-40 hours of game time. Also, there is almost no replay value. The game does include a collectible card system, where you can view the cards you have collected, but it does not provide much motivation for playing the game a second time through.
All in all, Lunar Legend is a fun, albeit short RPG, that can be a good introductory into the genre.