I'm posting my impressions here as well (since i posted on the other thread about the third party titles).
Was in an event earlier on.
(very brief) Impressions:
SFIV: Seemed like a very professional port, though I'm not a fighter gamer. 3D was kind of impressive in dynamic view.
R.E. ME: Some of the effects and character models were impressive, but I found the game a a chore. 3D was not that much of a story
PES: It was very impressive as all of the players in the field were "popping" out from the rest of the environment. Technically it seems like an upscaled port of previous gen PES. It played like a faster, smoother and graphically enhanced version of the last PSP/Wii games. But the viewpoint was locked (behind the player) and this is not how you play PES.
Pilotwings: one of the more impressive games. I had trouble adjusting my view to the 3D effect. In the end i "got it" and it looked GREAT. My only concern is content, it was too familiar because of the location and if it only features the "usual" challenges I won't get an impulse to buy it.
Nintendogs: very, very impressive. One of the best implementations of the 3D effect. I think this is because your eyes only have to focus on the cat and dog, the rest of the environment is very plain and does not get in the way. The dog and cat were ADORABLE and the 3D was eye popping. I almost want to get it now, despite having a dog and having played Nintendogs for so many hours in the past.
Ocarina of Time: The 3D was confusing and it was less impressive as a game from what I thought it would be. Still, it's an adventure I would gladly played again, and I think it will be great to replay on 3DS.
Steel Diver: interesting, but only the periscope mode was available so it almost felt like a mini game
DOA: didn't get the chance to play, but I think it looked very impressive graphically, almost a showcase.
Face Raiders/ AR games: very impressive tech demos and I think they featured the best implementation of the new tech. Mapping your face and seeing it grimacing on the screen in 3D and flying around the environment was hilarious and impressive at the same time. The AR game had a lot of quality and did well to advertise the AR capabilities of the DS
Kid Icarus: very impressive use of 3D and a blast to play, except from the confusing on ground controls. The graphics were very good but the game seemed to feature lower geometry than other 3DS games. My brain felt a little confused after playing with it.
3DS: Very solidly built, it oozes quality from an engineering perspective. I found the design screaming expensive but unremarkable. I think the black model is too... flat, while at least you get some personality with the blue color. It seems like an amazing little piece of hardware, but the 3D is a double edge sword, it's very impressive but it demands a specific positioning (which is very uncomfortable when the game features motion controls), while it obliterates the second screen. The 3D is so attention-demanding and it's so much different from 2D that you may forget that you're having a second screen underneath it (that happened with Steel Diver - I was almost annoyed that I had to look at the second screen from time to time).
All in all, I think 3DS XL will be the ideal version of this. I'll probably get around Easter, when the shop gets activated.