Hard to focus. It's not unusual for pocket projectors to be hard to focus, but the P2 Jr. is harder than most. The focus thumbwheel on the first test unit AAXA sent was flush with one side of the projector and resisted movement, making it hard to get to and almost impossible to control precisely. With a little practice, I was able to focus by resting my thumb on the side of the unit and using my thumbnail to move the wheel, but even then, focusing was a lot harder than it should be. The thumbwheel in a second test unit was easier to control, making the projector easier to focus but still not easy.
No zoom. As is standard for pico projectors, the P2 Jr. doesn't offer an optical zoom lens, so you have to move the projector to adjust image size. For image sources you have to connect to by cable, this may mean having to move the image source as well, depending on how long the cable is.
No meaningful audio. The P2 Jr. has a one-watt mono speaker, but the volume is so low that I literally didn't realize there was any sound coming from it until I held it about six inches from my ear. To make out dialog, I had to get even closer. Compounding the problem is that there's no audio out, which means you not only have to use an external sound system, but you have to connect it directly to the original source, rather than through the projector. Depending on the source and what connectors it has, that may or may not be a problem.
As should be obvious, the AAXA P2 Jr. offers a lot to like. Its got excellent data image quality, good video quality, good connectivity, plus the ability to read files directly from USB keys and microSD cards. It also helps a lot that it doesn't show many rainbow artifacts. It fits in a shirt pocket and has ample brightness for the size, particularly when using AC power. The projector would earn a few extra points if it were just as bright with battery power, but, of course, the lower brightness is a big part of what gives it a two-hour battery life.
The meager audio and the annoyingly hard to focus lens take a little of the shine off the P2 Jr., but not enough to keep it from being an impressive projector. The key point is that it gets the critical features right. If you need a usefully bright, high-quality image in the most portable format you can find, the AAXA P2 Jr. may well be the projector you want.