This kotaku review of Eyepet shows how camera based motion control can be problematic outside of a controlled environment. Lighting and backgrounds are very different from home to home. Sunlight can be very problematic as it is extremely bright. It's crazy when a game asks you to remove the furniture. That is stupidity.

http://kotaku.com/5402930/eyepet-review-his-masters-voice

Failure To Launch – The technology underpinning this game simply isn't ready to go from "tech demo" to "retail game kids will play". You know something's wrong when the tutorial tells you to empty your living room of furniture, and definitely know something is wrong when half of the basic tutorials end in acute muscular pain as the EyePet randomly fails to respond to the most simple of commands. In short, in the real world (and I tested it in all kinds of lighting conditions), the EyePet ranges from mostly obedient to unresponsive to downright oblivious of your presence.

Hardly definitive evidence, I think it works fine for me. It's not precise in any way, but it generally works.

Not the only reviews that have commented on the issue.

http://www.totalvideogames.com/EyePet/review-14668.html

Under the uniform fluorescent strip lights in TVG's virtually windowless office, EyePet and the PS Eye performed flawlessly. However, when EyePet took a trip to a normal living room with an everyday window the results weren't so impressive;

http://www.eurogamer.net/articles/eyepet-review?page=2

the on-screen results vary depending on the lighting. Sketches copied in daylight are crisp and near-perfect, while those done under electric light in the evening are often patchy and broken.

http://uk.videogames.games.yahoo.com/0c/eye-pet-faf80c.html

the Magic Card when doubling up as an on-screen gadget has an annoying tendency to vanish if the camera isn’t seeing it precisely. Lighting could be the problem, although we were putting EP through his paces at midday in a bright and uncluttered room.

http://www.psu.com/EyePet-Review--a008271-p0.php

the EyePet loves natural daylight. In fact he loves it so much that when we've tried to play with him in the evening he hasn’t wanted to respond to a good chunk of our commands under artificial lighting; that’s despite us plugging in two extra lamps in the living room to comply with game's request for ample lighting.

Oh I know others don't like it either. I have an office lamp sitting next to the TV, lighting the area I'm playing on. It's not a hassle to set up in anyway, and the response I get is fine.

I can play any time of the day, without it making a real difference.

I have had sunlight screw up the wii-mote as well before. So yes Sunlight has an effect on camera as well bad glare on TV screens.

Anyone who has played with the eyetoy already expected this. Some of those games were fun regardless

So I am guessing that natal will not fare any better, since it also uses a camera.  The funny thing is camera controlled game play is never going to be as responsive as a game controller, this is not the intention, it is really used for further interaction within a theoritical game space.

IR camera do fair a little better since a IR lens filters out all other light. But Natal isn't trying just to track a glowly IR light but your body so it will probably be more acceptable to other IR sources like sunlight. Natal already had some trouble with how IR reacts with different skin color.

Eye pet does tracks your whole body I believe, because the ps3 wand is not out as of yet.  Then again I know you can draw stuff and bring it to life in the Eye pet game, I just believe that any camera controlled game will not have true 1:1 interaction.....not this generation anyway.  Heck the original wii mote does not do 1:1, that is why they brought out the Wii mote plus (I think it is called).

"EyePet ranges from mostly obedient to unresponsive to downright oblivious of your presence."

just like a real pet then? :D

so, what is wrong with making space in front of the tv for the game? what did they expect? and its not really a huge space that is needed, or did they also put their wii-fit board on the couch-table because there was no room on the floor? actually you CAN play eyepet on a Table, if you set up the camera in the right way, but since that requires commons sense i don't see that happen.

as for the light, i believe the camera tries adjusts itself to the given light in the room when it sarts up!. if you have changing light intensity, like you start with daylight and it's getting dark, it can't keep up, same if the room is too dark from the beginning and you add light AFTER you started the game, that won't work either.

Edit:

"the Magic Card when doubling up as an on-screen gadget has an annoying tendency to vanish if the camera isn’t seeing it precisely"

the magic card doesn't work well, when the camera can't see it? what a FAIL! Shouldn't it be able to GUESS where i am holding the card? ?