I was absolutely in love with the Game Boy Advance and thought it was the best handheld ever created. I got the DS (original, fat, ugly gray) within a week of launch, and played EVERY meaningful game for the system up till late 2008. You could say I burned out of handheld gaming pretty hard, seeing as I've had Game Boys of all variants since like 1995 or something. I don't own a Game Boy Advance or a single game for it anymore, nor do I have a DS. I sold them all because I was so totally done with them.
 
So although the 3DS looks very promising and great on so many levels, there are a lot of things holding me back from jumping on the bandwagon anytime soon. I love the N64 updated games like Zelda and Star Fox, the new entries like Super Mario, and ports like Street Fighter IV and Metal Gear Solid 3, but I've also been burned pretty bad by Nintendo's stupid prerogative with the Wii and all those lame casual sensitivities and the lack of decent online features.
 
SO, here's my list of things that will get me into the 3DS for sure.

• A revision or fix for the battery life issue (5 hours?!? Are you joking?)
  
• A couple serious killer apps (Super Mario looks like it could be cool.)
  
• Bigger screens - the touch screen is smaller than the one on the DSi? WHAT? I don't need DSi XL proportions, but decent big screens are a MUST.
  
• Solid lineup of downloadable games (along the lines of the XBLA and PSN)
  
• GBA games added to the virtual console (specifically: Metroid, Mario & Luigi, WarioWare, Advance Wars, Castlevania)
• Any sign that Nintendo is going to allow DLC for existing games, plus patches and updates
• Achievements or something like that would be cool, especially if there was a point to them (like in-game bonuses, special Club Nintendo products, etc.)
  
• Metroid Dread. Done.
• Also, Picross 3D 3D. Make it happen. Super Smash Bros. would be tight too, maybe.
  
• Price drop. $250 is way too steep for what you're getting. I'd gladly just take a DS2 without the 3D for less. As it stands, I could get a PS3 for less, so...
• UPDATE: I have heard reports that emulation of old DS games is fairly poor, and that's bullcrap. A revision would have to fix that.
  

Both my DS Lites are on their last legs with the shoulder buttons working off and on, or not at all unless they're blown into, NES style, first. I'm looking forward to upgrading if only to play some upcoming DS games with functioning L & R Triggers.

" You forgot to list "Women hired by Nintendo to deliver it to you in a mutually awkward and embarrassing fashion" "

Nintendo? DLC? Achievements?! 
 
Sorry, but I think you're asking too much of them.

Meh, I'll stick with my iPod touch for now.

Picross 3D 3D?! Isn't that likely to tear a hole in the space-time continuum, or something?

Good games are pretty much the only selling point I need.  Give me an original Zelda, another Mario & Luigi sequel, some Warioware wackiness, and port that Phoenix Wright/Professor Layton game and I will gladly buy a 3DS.

Since i havent played no DS games before, instead of buying a DS, i opted for buying a 3DS and playing back logs of DS games :d

Even though I know it's usually a good idea to wait until the second version of a Nintendo handheld, I'd be willing to take the plunge sooner once the price drops a bit and there are a good number of RPGs out for the system since that's all I play on my DS Lite anyway.  Don't get me wrong, I love playing RPGs on my DS which is why I am eager to see what will follow for the 3DS (and eventual NGP).

" Good games are pretty much the only selling point I need.  Give me an original Zelda, another Mario & Luigi sequel, some Warioware wackiness, and port that Phoenix Wright/Professor Layton game and I will gladly buy a 3DS. "

I had to sell my DS Lite to pay for my Xbox 360 replacement. Thus, I am handheldless. Thus, I'm shooting to buy it near-day-1 with Pokemon: Black/White & Okamiden. :D

Let's stop kidding around. What's REALLY going to move units will be Pokemon.

What I want from a 3DS? I can tell you what I don't want and that is yearly revisions that end up fucking over early adapters.

I might actually be more interested in portable DLC than I have been with console stuff. It would be cool to have a version of fallout in your pocket that you could hop into whenever. DLC would work really well in that scenario.

I'll probably buy one when Zelda comes out, but until then, I'm seriously thinking about buying a new cell phone, specifically the Experia Play, for no reason other than emulation with proper controls. I think it'd be pretty rad to have every NES, SNES, Genesis, GBA etc games on hand at all times, with their proper control schemes intact, especially with all the time I'll be spending around my college campus next semester. Maybe I'll finally finish Super Mario RPG.

Oh no I have to wait 5 extra seconds to start the game, what ever will I do! *faints* 
 
Jeez lame excuse much. Oh and there's a video on Nintendo's website where "achievements" are directly mentioned. So who knows what that means. All I want are Friends Lists (which is has) and Voice Chat (which it may have). Oh and I'm not bothered about the battery life, if it really is a problem imma just get one of those Nyko Power Pak+ cause they look sexy and aren't really expensive.

" Oh no I have to wait 5 extra seconds to start the game, what ever will I do! *faints*  Jeez lame excuse much.