Focus. Adjusting focus on pico projectors is never fun, but the E3 has one of the least enjoyable focus adjustment controls yet. The knob is small, with only a small portion exposed. The action is sticky, so you'll need to put some force behind it in order to adjust the dial. And despite the little dial, the focal range is actually quite long, so you might find yourself cranking away for a while before the picture becomes clear. It's also worth mentioning that the projector will not focus at distances less than about eight inches, so if you find yourself unable to focus, try moving away from the screen a bit.
Battery life. Last year's E1 used AA batteries and had a lifespan of roughly four hours on a full charge. We were hoping to see the same out of the E3. Unfortunately, higher brightness and higher resolution come with higher power requirements, so the E3's battery life is only about 90 minutes on a full charge. If you plan on using the E3 to watch a full-length feature film, you have two options: either leave the projector plugged in to the AC adapter the whole time, or pick a short movie.
Menu. The menu system on the E3 is not unusual; it is divided into subcategories based on media type, with subheadings for movies, music, pictures, et cetera. However, the actual layout is highly derivative of Sony's menu system for the Playstation 3, only less elegant. The other annoyance is that, should you want to adjust anything during playback, bringing up the menu will pause your content, though the menu itself is translucent. There does not appear to be a way to turn this off. This really becomes bothersome when what you want to adjust is volume, since you can't adjust in real time.
Charge over USB. The E3 can be charged using a USB connection from a computer, but this takes much longer than using the AC adapter - 8 hours instead of 3 hours. This isn't the fault of the projector, though; USB simply carries a lot less power than a wall current does. The downside of this, though, is that running the projector tethered to a computer cannot keep up with power demands forever. While you can use the projector indefinitely while it is connected to the AC adapter, using a USB connection gives you an extra hour of battery life if you start from a full charge. After that, the battery simply cannot keep up anymore and the projector shuts off.
The Favi E3-LED-PICO is an interesting little projector, with very high brightness for a pico projector in a package tailored for movies and video. Great image quality makes the projector a fine travel companion for entertainment junkies, while the highly capable onboard media player makes the E3 easy to use without a lot of work beforehand. On the downside, the projector's high brightness means it chews through battery power at a prodigious rate, so anyone looking for the full-length feature film experience will need to provide some form of supplemental power. At only $350, the E3 is a solid, inexpensive option for portable entertainment.