I'd be doing you a disservice if I said the Nintendo 3DS was perfect.
There are a plenty of reasons you might not want to buy a Nintendo 3DS and I want to make those reasons known.
Even though I'm a fan myself everyone's different and what's important is that you choose yourself how you spend your money and whether or not the gaming experience the 3DS offers is worth your attention or consideration.
Here are five reasons why you should not buy a Nintendo 3DS:

1. Stereoscopic 3D doesn't matter to you.
   Unimpressed by Avatar? Didn't care for How to Train Your Dragon? If stereoscopic 3D content is just not for you then it's likely the 3DS will not impress.
   I'm on the side of the fence that loves the immersion 3D brings, but if you're not on that side don't feel pressured into liking a technology you don't care for.
   
2. You're a casual gamer.
   The Nintendo 3DS offers plenty of casual gaming experiences, but the platform itself could be seen as overkill for most casual gamers.
   If you're simply interested in playing Brain Training or older Mario titles then a standard DS or DSi would be a cheaper (and probably better) alternative.
   
3. Young children will be playing it.
   There's no strict rule against children enjoying 3D content, but Nintendo themselves have advised that children under the age of seven either avoid or limit their time with the 3DS to prevent possible eyesight problems at some point down the line.
   
4. You're concerned about your eyesight.
   It's not just young children that may be effected by eyesight problems.
   Moderation will surely help avert any long term issues, but if you like longer gaming sessions and are worried your eyesight may deterioriate then the Nintendo 3DS may not be for you.
   Studies regarding the effects of 3D content on our eyes are currently inconclusive though.
   
5. Money is tight.
   Responsibility before gaming.
   It sounds preachy but no video game console is worth going into debt for or worth putting yourself at financial risk for.
   While the Nintendo 3DS may not be as costly as other entertainment mediums, the price of games and accessories can add up.
   Make sure you weigh up all factors before making a purchase, and don't hesitate to be patient until a price drop or until you're in a better financial position.
   

It's no secret that I think the Nintendo 3DS is a great piece of technology.
It's fresh, innovative, and has a brilliant library of games.
Just make sure you don't give into peer pressure or the notion that the 3DS is literally a "must have" item.
It may take on the qualities of something you need but if you're not that interested in the Nintendo 3DS then you don't need to buy it.