Without a doubt! I dont think its needs to be put on big screen when the decision is being reviewed like in Rugby (mainly because not every football ground has these...in fact i think their quite rare thinking about it). However it is essential for the game to be fair.
In all honesty, how many games will we actually need it??
I agree it must only be goal line though and not offwide, off the ball incidents etc. We've got allow room for some error!!
Unless they put a cap on the number of appeals, like in Tennis?? But how this would work with offsides im unsure, as the lino wud flag, players appeal and by this time the advantage has gone so seems pretty pointless.