I might have said "Recommended for Fans" (same as I gave to Milon's Secret Castle), but I can't fault Zach. What he wrote about Metroid is totally correct. It was an ingenious game that influenced countless others and spawned sequels that I consider to be some of the best games ever made. But Metroid is a game you would play in a Gaming History class to learn about game design. It's not very much fun on its own merits, unless you are extremely patient and forgiving. Back in 1987, I was. Not only am I twenty years older now, but the state of gaming has changed so much that it's hard to accept Metroid's many flaws, even if it is revolutionary. I believe Metroid's ideas and ambition far outpaced the technology available to create it at the time. Super Metroid was when the tech finally caught up with the vision.
Also, I want to second what Windy said. These are recommendations only. In the case of Metroid, you are much better off finding a copy of Zero Mission and playing that on your GBA or DS. It's the same game but expanded and improved in every possible way. And you'll still get the original, just so you can play it and be disappointed. Alternately, you can put Metroid Prime into your Wii and play the original Metroid that way, just like I did yesterday when showing a friend what all the hoopla was about.