Konami continue to make fantstic 2D Castlevania-games, but the 3D Castlevanias suck

I can't think of a single game which has improved gameplay after switching to 3D. Can anyone?

^mario 64

 ...every game that features cars and planes ??? ...there are more but with cars and planes there is just no question... you need all three (or four) dimensions...

Mario 64 didn't improve the Mario gameplay; it changed it.  The goals and level design of the 2D and 3D games are radically different.

Most of the good racing games like Mario Kart and F-Zero were already partially 3D on the SNES.  If you're going back to the NES games then you didn't really have racing games so much as on-rails dodge-a-thons.

As for flying games, the 2D ones were already attempting to fake 3D as early as the NES or going the side/top-down shooter route. 

depends on the game

2d has a good argument for platformers: marios, castlevanias, rayman 1, etc while 3d only has a few great platformers

fps is better in 3d, as are racing games

zelda is great in 3d, even if my fave zeldas are lttp and phantom hourglass

sports games are better in 3d than 2d

it really depends on the game and how the developers do it

 Only partially. DK64 was a wonderful and memorable game, IMO. I also know a whole mess of other people that agree with me on that.

 Every other DK3d game, though, has admittedly sucked. Nintendo needs to get a clue that this bongo blast concept blows. Innovative, sure. But is innovation always good?

And as for Mario 3D and Zelda 3D being a success, don't get me wrong - I agree. But let's remember that New Super Mario Bros and Zelda: Phantom Hourglass are some of the best handheld games in history.

3D fighters are hardly a "fail". 95% of fighters released are 3D now, and millions would consider them a huge success. DBZ Budokai, for instance, captures the precise feel of the anime, and Soul Calibur wouldn't have been able to represent the martial arts half as well as it does if it were 2d.

 FPS can't exactly be done in 2D, Fastrabbit, so that's a really poor point.

^^ I agree with everything but the 3d fighters part, fighers never got any better than Street Fighter 2 IMO, since 3d did nothing to improve fighters I see it as a failure... sure there are some great 3d fighters but the question was weather they improved... and they didn´t...

I think the whole 2D vs 3D depends on the game itself and of course the developers. Mario moved successfully to 3D (SM64/SMG are proof) and they were developed by Nintendo, if EA were to do a 2D-3D then they would probably cock it up.