Pros: Stunning picture.
Cons: Fan loud, video offset is very limited.
The bottom line: An almost perfect projector.
Make no mistake about it, if you can get this projector setup in your home theater the picture is STUNNING! But getting it setup is no easy task.

SETUP
The Optoma was rushed to market to beat the competition to the 1080p projector market. To do this, Optoma took some shortcuts and used an existing shell to house the HD81's components and most importantly the new TI DLP 1080 chip. The following occurred in doing this:
1) The projector must be mounted ABOVE the TOP of your screen. How much? 36% of the screen height higher. So if you have a 5' high screen you must mount the projector 21.6" ABOVE the top of the screen. Many people with big screens and 8' ceilings will have to double check these calculations to be absolutely sure it will fit in your room.
2) You need to center mount the lens to your screen.
3) You need a long room - the projector needs to be mounted ~ 2x the width of the screen. So if you have a 10' wide screen, the projector needs to be between 19' and 23' away from the screen.

Is there room for error? A bit, you can adjust the image both vertically and horizontally, but only in very small increments and to a maximum of about 5" (though this varies with the distance of the projector from the screen).

MORE SETUP
The great news about this projector is that it comes with a separate upconverter, which you can plug in 3 HDMI sources as well as a few component sources, vga sources and S-Video sources.

This upconverter uses the Gennum chip, and it does a stellar job. More on this in the viewing section. But it does have a drawback - you need to run an HDMI cable from the box to the upconverter (no big deal or how else would the projector get the video), but you ALSO need to run a DB9 (serial) cable between the upconverter and the projector. Optoma gives you two 6' cables which are useful only for testing because they aren't remotely long enough for a projector 20' away from your screen and 10-12' high. So price in two of these cables for the length you need.

Viewing
This is where the HD81 shines. The images are STUNNING! I have to put a big exclamation mark after the word stunning because they just pop out of the screen (I use a .95 gain screen, 126" diagonal, 16:9 format). I'm getting about 16 ft lamberts with a new bulb off the screen so it is very bright and very beautiful.

Putting in my directors cut LOTR DVDs resulted in an image that will literally make you wonder why EVER pay to see a movie in a cinema again. I could watch upconverted DVD forever! Until, of course, you see HDTV - which is EVEN better (but not by as much as you wouldn think, thanks to that incredible Gennum upconverter box they give you).

Out of the box the HD81 is a little bright and exhibited some red push, I calibrated it using the AVIA test disc and it improved. Regardless, even if you do no calibration, this projector produces one amazing image out of the box.


Ease of Use
Very easy menu to use. The manual comes on a CD, so I suggest you print it out for easy reference. You can adjust settings for specific inputs and save them to one of 3 user settings as well.

You can spend hours learning all the functions, but their layout and menu system is very intuitive.

Not All Good
Even if you're lucky enough to have a room that can accomodate this projector, it has its issues. The biggest one is fan noise. My room, using my SPL meter, is below the meters lowest reading when no equipment is on (e.g.: that means its somewhere between 10 db and 25 db). To my ears its completely silent. Power up the HD81 and from 5 ft away I measured 36db and from 10 ft (that's the front row) I still measured 33db.

If you don't know what this means, I'll tell you. During quiet scenes (like suspenseful ones) you can hear the fan humming away.

The other minor issue is that you can't (as of this writing) flash the bios yourself. I haven't experienced any problems, but a few people that have actually have to pack up the unit and ship it back to Optoma. Personally I find this unacceptable, since I spent hours making sure it was perfectly level on my mount.

Conclusion
An absolutely stunning picture, but a slightly flawed projector. If you don't watch a lot of silent or suspenseful movies you should get this as soon as possible.