How long would it take for the game to download though. Would it not be quicker to just buy the cartridge? Are there any advantages for eshop download, other than you can do it from home?
It really depends on your ISP. But even if you have a really fast connection, downloading it on launch day is really slow. Considering the size of the game, it might take an hour or two.
As for advantages, it's just the ease and convenience. Since Pokemon is the type of game you would normally play on a daily basis, having a digital copy of the game would be great. Still, it depends on the player's preference. I prefer getting a digital copy because retail copies are far more expensive in where I live.