Media Decor The answer is most likely yes. In the above photo it appears that there is a speaker bar above the TV and a slotted vent above the speaker bar. Because there is a mantle and the TV is recessed, there should be no heat issues (especially with an LCD TV.

If you care to send a straight on photo with some basic dimensions, we can draw it out for you.

bepsf Depends on your fireplace -
A 50" wide TV would appear ridiculous over a 42" wide mantel and a firebox that's only 30" wide...
...however, with a firebox that's trimmed out with a wide tile or stone surround, and with a mantel that runs the full width of the chimneybreast - it would appear appropriate.

The rule of thumb is simple: If you wouldn't have a mirror or painting that large over the fireplace - you shouldn't have a TV screen that size either.

hilltop1155 I do think it's too high for standard-height seating, although the problem can be mitigated somewhat if the seating from which the screen is viewed is far enough away from the TV. It also appears that their center speaker is above the TV, and if that is the case the sound may not be optimal from this position either.

COASTROAD Hearth & Patio Top of an average, traditional mantel is about 54" off the floor. To achieve a lower TV viewing height, it appears this mantel shelf in the photo above has been dropped down to about 42" off of the floor.

Beauty is in the eye of the beholder, and the continuous line through the base cabinets at the side make for a a pleasing composition here, As well as the finely detailed trim work.

Here is the caution: be very careful about observing required clearances around any fireplace, wood or gas. The lower the shelf projection is, the more likely it is to get too hot. Start with the required clearances, and draw the wall elevation out completely so you can see how the proportions work out.

Sheila Schmitz The two built-ins need not be identical; you could put a small desk on one side. You might even consider a flip-top desk you could fold out of the way when not in use. But why not let the desk extend to the end of the wall? Any unused work surface would make a nice space for books or a vase, and tie in with the display area on the other side of the fireplace. Please let us know what you do!