Since I don't have the "warm fuzzies" of Earthbound nostalgia love, I think my perspective is interesting. Many times i've tried to head back into older titles and haven't loved the result. Some games from the NES or SNES era don't hold up as well as others and that's disappointing to experience. That said, Earthbound moves beyond all that as it holds up really well now.
From the initial screen, to the first parts discovering your mission, Earthbound weaves interesting story telling with superb art and music. Since Earthbound came out after the Super Nintendo was established the game reflects this by providing a really polished experience.
If you haven't played the game and are looking to check it out, I recommend you do. You can pick it up on the Wii, Wii U, Gameboy Advance or Super Nintendo. Each version is basically the same, but some alterations were made from the initial Super Nintendo version to accommodate the platform.
Oh and by an awesome set of circumstances, Nintendo has decided to post the entire Nintendo Power Earthbound guide online, for free.
http://earthbound.nintendo.com/playersguide/
Oh and checkout STARMEN.NET, an awesome community of Earthbound and Mother fans.
http://starmen.net/

Someday I need to get around to playing this as well.
Yeah, it's been fun as I've been playing it for the last few weeks.
It's a nice change of pace from more "serious games."