Overall, the HD20 is sharper than average. It can't quite match the "razor sharp" look of the best in the price range, such as the BenQ W5000, but does a very good job overall, and, upon close inspection, comes across a little sharper than several of the best selling 3LCD competition, including the Epson and Panasonic.
The Optoma really lights up. There's a fair amount of light exiting the front vents, with a pinkish white color. It mostly throws that light outward toward the right, but forward. You will be able to spot the light leakage in a darkened room if your walls are light colored. Not impressive in this regard, the HD20 leaks more light than any other recently reviewed projector. Light leakage out the lens is there but minor.
DLP projectors seem to have more basic image noise than other technologies, and the HD20 is no exception. Still, it's pretty clean. I never felt the need to engage the noise reduction circuits on the Image/Advanced, menu. No particular issues with any motion artifacts to report. Definitely not the most refined image processing here, but it does the job, and I don't consider image noise to be an issue, especially in light of the low cost of this projector.
Ouch! OK, if there's one real, achilles heel of the HD20's home theater performance, it's the fan noise. It is definitely one of the noisiest home theater projectors out there. I haven't yet seen a noise spec, but most likely, at full power, the projector is probably somewhere between 32 and 35 db. That's probably a non-issue in typical family room (mulit-purpose) usage, but would be considered very distracting for those in a more dedicated environment, or when watching quiet scenes in a movie. If you think you want a quiet projector - then the Optoma HD20 is not going to be for you, as almost all alternatives are anywhere from a little to a whole lot quieter, with some projectors under $2000 a full 10 db quieter (and that's a dramatic amount - considering most projectors drop 3 to 5 db, going from full power lamp mode to low power).