Well, the Projection TVs are those big screen TVs that have a backscreen projector (you don't see it) and they are kinda thin compared to normal TVs, their sizes vary between 44" and 66" I guess, and for the "you cant see it at a certain angle and the cloudy image quality" problem, if you buy a high quality TV, it doesn't have this problem, or atleast, not as bad as the lower quality ones.
The advantage of buying Projection TVs is their price, their so cheap compared to Plazma TVs, plus, the Plazma technologi isn't good enough for use yet, because Plazma TVs gets deteriorated by time and the screen looses its colors in about 5 years (it becomes gray), so if you wanna repair the TV, you gotta pay about 600$.
So, the choise is yours.