Ah, back to the good old days of the first three Pokemon games. Sure, they're a bit old-school, but whenever I have the free time to do things, I go back to my gold 'ol Blue version just to see what I can do. I have to admit, it's fun to turn that game back on, look at the funky sprites, and just enjoy a good old catching fest.
For a game made strictly for GameBoy/GBC, the graphics are pretty good. I have to admit that some of the sprites scare me, though, like the demented Golbat who looks like he wants to eat you. The blue tint to everything makes me thankful for the full color on the later games, too. I mean, blue's one of my favorite colors, but there's a limit to how much I want to see in a game!
Personally, I kind of like the music. It's catchy, fits the themes, and is just a nice little background thing while playing. The attack sounds aren't all that bad, either, though considering the same sound is used for just about any beam released, it can get a bit boring. I do like the sounds for the water attacks such as Surf and Hydro Pump, though.
As far as gameplay goes, it deserves a pretty high score. You have to catch as many Pokemon as you can, manage how many items you buy and carry, level up your Pokemon to make them useful for later battles, beat eight gym leaders as well as zillions of random trainers and the Elite Four, and find a way to make yourself better than your rival. It's a good way to wittle your time away and you can never really beat it the same way twice. Plus, games such as Digimon World 3 have actually taken the gameplay from the Pokemon games and used it as their gameplay.
I've been able to beat the game several times, but there is a limit to how many times I'll WANT to play it. After all, even though there's always a different route to go in training your Pokemon and winning the game, it's always the same end. You beat the Elite Four and your Rival, you get into the Hall of Fame, you look for the rest of the Pokemon that you didn't catch beforehand and get your diploma from the designer in the mansion in Celadon, and you're pretty much done if you don't go back for the glitches. Of course, then you run the risk of ruining your game, but hey, it's still better than nothing.
Really, Pokemon Blue is a pretty good game, especially for it's time. Once you put aside the early sprites and the predictability of the plot, it's a good way to keep entertained. Even though I have some of the newer games, I still find myself going back to my Blue version because it's nice to go back to the roots of the games. If you haven't played Red, Blue, or Yellow before, I suggest at least renting it to try it out.