it costs too much=aleady a fail
True, but same thing happened with DS Lite (costed more than DS Phat), and that didn't have a problem

launchs with 2 colors why not copy the colors of ds lite
DS Lite started with two colors too (or was it just one)... give it time

the cameras horrible
The cameras take pictures that are the maximum resolution of the wii (640x480), it is obvious that the cameras main purpose aren't for going on the computer, but for being transfered to the wii photo channel

the sreen size increase is pointless come on .25 more inches
What did you expect? It is going to be playing the same games as the earlier DS', if they increased a lot then the games would look horribly stretched.. so you might be wondering "why bother such a small amount", there have been complaints, mostly with elder people, that the screen is too small and find it hard to read the text, this small increase was probably surveyed and found to be the optimal size for 'efficiency vs. cost to manufacture'

NO GBA SLOT
There are two previous iterations of DS' and two or three iterations of GBAs on the market, if you don't have any of them, you probably won't have GBA games either. 

What you are forgetting is that this upgrade is PRIMARILY to target the people who weren't interested in the DS Lite, hence the extra features that may seem gimmicky to us .. I personally can only see one reason why I'd buy it, and that would be completely depending on whether or not the DSi applications from the online store are good enough to warrant a new portable console