Help me decide if I should buy one, and why
well, it's not the greatest piece of hardware, but many people like it/enjoy it because it's intriguing. Each game has its unique style and difficulty therefore it's appealing to many different "crowds". There is nothing like it. It gives video games a whole new feel.
Its not for everyone. Some people complain of headaches while using it.
...Others are just ignorant. "Oh noes! It doesn't have 65536 bit CPUs and crappy FMV games! It suxx0rz!
The only way you'll find out whether you like it or not is to try one.
I posted elsewhere on this subject, but I'll reply to you directly anyway...what made it cool was that it was unique. Utterly unlike anything else, totally weird, love it or hate it kind of a deal. It failed because Nintendo fumbled the ball on the marketing. This system needed something to take off and Nintendo hadn't figured it out yet. If they had held on and worked hard to produce more solid franchise games, I believe it would have been a success.
If you have strange tastes, if you "get" things that most other people don't get...by all means, get one. If you are more of a mainstream guy (and hey, nothing wrong with that) spend your money on something else.