i game on a 40" lcd 1920x1080.
is it too large? yes and no.
in general text, and everything else might not appear as clear as on a smaller monitor of the same resolution (because of pixel density) however everything is much larger.
rpgs, strategy games, sports games, etc all act in much the same way as normal monitors.
fps games are harder to adapt to. on smaller screens your eyes focus directly on the center of the screen area (which usually equals the screen area) so you don't have to rely on perepheral vision at all to respond to movement. on a large screen the effect can be overpowering at first and you must learn to use perepheral vision to see the edges of the screen. i prefer playing fps on a smaller monitor but for my general useage (other games, movies, web) the large monitor works fine.
for quality a monitor like the dell 30" is superior, however at much personal expense. ($1000+). i would have went that route if i didnt require my screen to be half computer/half movie theatre as that resolution would make even bluerays look inadequate at fullscreen.