Though mine is still in process of being shipped, Match received their Kindle Fire devices today. I got to play with it a little and test some pages with it. I also needed its user agent string, which I couldn't find on the web. So here it is:
Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_6_3; en-us; Silk/1.1.0-80) AppleWebKit/533.16 (KHTML, like Gecko) Version/5.0 Safari/533.16 Silk-Accelerated=true
User agent strings tend to be full of lies anyway, but I expected a very Android-like user agent string. I was surprised to see the Macintosh-ness of it. Anyway, there is the first gen user agent string of the Kindle Fire if you are looking for it.
As for the device itself, I like it so far. I was surprised at the heaviness and the usability definitely needs some work in various areas. It was also frequently choppy so could use some more power. But still, it appears to be a nice device on first usage.