I use this primarily when I travel, it makes for a great TV, second monitor, or even better when sharing media with a few people.
The brightness is really great, it's definitely bright enough to be seen well even in a dimly lit room. This isn't a full size projector, so I wasn't expecting much, but it performs great.
The unit has HDMI and VGA which are life savers, HDMI accounts for 90% of my use, and USB the other 10%. It's handy to be able to plug in a USB drive and play any video files off of it.
If I had to knock it I'd say the fan is a little loud, but that's nitpicking.
You'll be amazed at how small this device really is. It will literally fit in the palm of your hand. It's battery powered which enables mobile uses. You can run videos or pictures on a whim, or use it for business related presentations and graphs. Has all the connectivity functions, HDMI, USB, and etc.
Got this cause it was in my price range and it was worth the buy. I bring this projector with my everywhere especially on my camping trips. It last for over an hour long letting me watch movies outside at night. Can't go wrong with the P4X!