Currently there are only a few apps that are supported by Chromecast- Netflix and Youtube for iOS while Android supports two more apps Google Play Movie and Music. However, Chromecast currently only supports 720p while streaming via browser and 1080p via cloud. Also, if you want to stream your personal videos, pictures etc you will have to first upload them to cloud. Still, $35 makes it affordable for the masses and we can expect sales to further escalate in the coming days. Netflix even offered free three months streaming services for initial buyers.
Chromecast will be competing with its more expensive competitors (set-top boxes), Roku 3 and Apple TV. However, all depends on what your needs and preferences are. If you are an Android user/fan you save some dough by sticking to Chromecast until it releases more apps for android. Apple fanatics will probably stick to Apple TV which allows streaming from all apple devices and itunes and people who are willing to forgo YouTube and iTunes for more channels (750 channels) will prefer Roku 3.