The Fire is pretty awesome for $199. But it lacks several features that I think would put it right over the edge. I also have an older Nook Color. It has the one thing that I wish the Kindle did. An external MicroSD slot.
The Kindle actually has MORE memory for media/apps than a Nook Color does by default however. The Nook only allows 1GB of its 8GB of memory to be used for user loaded content. The Fire has about 6GB for Amazon or user loaded content.
With the whole "cloud" thing, as long as you have a network connection, you really don't need much storage so its a nit picky thing.
The fact that it will be the best selling Android tablet guarantees that it will have great support in the modding community. I'm 100% positive that Cyanogenmod will create an Android OS install for it. As long as I can still do all the Amazon Prime streaming with a modded OS I'm game!
I've already "rooted" it and side loaded the Google Market and some Google apps. Its not perfect yet, but new tweaks and hacks are coming out everyday for it.
The bottom line is that if you are already an Amazon customer (especially if you are already a Prime user) the Kindle is spectacular.
If you have nothing invested in the Amazon eco system than it is cheap enough at $199 to make you want to be invested in it.