I grabbed one at my local Best Buy literally minutes after they pulled the cases off the truck. For $35, I feel it's a good investment although it is limited for the time being. Part of it may also be that the only computer I've tried it with so far is an older 2007-era Vista model (and I get the impression Chromecast was designed for Win7 and above). Also, I have the entry-level LinkSys WiFi router, so it's not really certified for HD streaming.
First, the cons:
1. Very laggy performance when "casting" from my Vista desktop's Chrome browser. Hulu Plus is unwatchable. YouTube and Netflix fare better.
2. Minimal Android app support thus far (only Netflix, Play Movies/TV, Play Music YouTube currently work).
3. No "casting" support for Chrome Mobile yet
Now the pros:
1. Unbelievably simple set-up and pairing. Took less than 5 minutes using the new official Chromecast app on my Galaxy S4. I've had Bluetooth devices that were a bigger hassle to pair than the Chromecast.
2. Streaming Netflix, Play services, YouTube from my S4 and my Nexus 7 were incredibly fluid, easy to navigate.
3. You can initiate a stream and then do other stuff on your device without interrupting the "casting". Simply pull down the notification shade, and there is an actionable Ongoing Notification for the stream.
The fourth "pro" is the three free months of Netflix, but news just broke over at droid-life.com that Google is axing that promotion because it was essentially costing them way too much due to "insane demand". Best Buy did e-mail me my discount code already, and it did work so early adopters may luck out.
Yes, there are some bugs in the system, but I feel they can be easily remedied with future software updates. Also, bear in mind that these are just hitting the market. In fact, are they even supposed to be in wide circulation now? Was there a release date given? Possibly next Tuesday with the N7 (2nd generation)? Keeping that in mind, it's possible that there are Chrome browser and/or app updates coming in the next few days that will add Chromecast support.
For example, Pandora was named as one of the programs supported "out of the box", but there hasn't been an update released that allows this.
In the end though, it is only $35...hardly a huge investment and worth taking a risk on it.