I use Miracast regularly for watching YouTube videos. I also use it for movies once in a while. I like it because of the convenience it offers compared to my existing alternatives (WDTV & PS3 YouTube apps). I recently bought a Chromecast. So, I expect my dependence on Miracast to go down.
With Miracast, you get what you see in tablet. So, I assume there won't be any DTS audio.
I faced a few head aches when using Miracast initially:
1. It wouldn't connect reliably. I used to get stuttering in the video and audio. With the latest PTV3000 firmware, its working fine for me (see my post here
2. The screen has to remain on all the time when you are playing something. To work around this, you will have to root your device and install Screen Standby
3. The TV resolution and Nexus 7 resolution should match. Otherwise, the video will get boxed. To work around this, I am using this
app. Whenever I connect to Miracast, I use that app to manually set the Nexus 7 display resolution to 1920x1080, and revert to default after disconnecting. I came across another app
that can do this automatically, but didn't try it because of its $6 price. Note that once you change the resolution, the icons will get misaligned (until you change it back).
4. I would also recommend the device be connected to a charger. I bought a Lugulake wireless portable charger so that I can leave the tablet on top of it without having to worry about battery.