Tsk, Tsk! The front grill of the projector leaks a fair amount of light for a home projector. It's mostly off to the front right. In a really dark room, with a dark scene, you can spot it. For the typical use of this projector, I don't see it as anything to be concerned about.
After additional consideration, I have to admit the light leak lights up the front of the projector in a colorful (reds orange and white), and impressive way. Gives the projector some real character.
It's definitely not quiet at full power. Small single chip DLP projectors tend to be a bit noisy. At full power, the Optoma HD23 has to be considered one of the noisier around. Part of the trade-off is the HD23 projector's very small size. Larger projectors have more room to baffle the sound. In other words, this HD23 is fairly typical for projectors in this price range, even if there are dramatically quieter projectors at 3 times the price. Perhaps we should say that audible noise is one of the things (not the key difference) that separates home theater projectors from home entertainment projectors.
I observed that there was a whine that varied in intensity, and at times, rose to be heard above the fan noise. Even so, if you're watching sports, or most TV, you probably won't notice unless you are sitting real close. It's no louder than my PS3 when it feels it needs to cool down.
The good news: Drop lamp to low setting and the projector is reasonably quiet. The pitch is low and you have to get close and listen to hear any whine. Back to my PS3, vs. my PS3. When you are in Standard (low power) on the HD23, and that same PS3 kicks it's fan up, the PS3 easily drowns out the HD23, even though the PS3's 10 feet from my seat, and the HD23 is less than 4.
In other words, don't sweat it. For most viewing, you should find high power to be fine. If you are watching the kind of soft spoken movie with lots of very quiet scenes, and you notice the projector, try low power!