overall its a pretty good game. it gets kind of boring the farther you go. the graphics improved a lot from the first two installments. its generally for younger kids. umm... its obviously not for serious gamers (but keep in mind: its GBA we're talking about here. nothings serious).
This is one of those games that were originally on the old Super Nintendo, and were rereleased one the game boy advance with worse quality, but with xtra features. I really don't care for those anymore. Like the previous gba DKC ports, this one has tuned down graphics and music quality, but what is even worse is that they actually changed the entire soundtrack. The original SNES DKC3 had much better music. Also, not all tracks were recomposed, some places that originally had their own music, in the GBA version, they just slapped another one of the new tracks into another place, which is pretty lazy work. Also, they put a new world in too, which kind of makes it look like an entirely new game. I'd rent it first and try it out before I drain $30 from my pocket if I were you.