The HMX-H304 has one of the larger display diagonals (3 inches) amongst medium total megapixels camcorders of this age. Across all the camcorders of a similar type and age to this camcorder the display diagonals range from 1.5" to 4", and the average display diagonal is 2.8".
It may also be worth also looking at one of the other 3" screen size video cameras currently available including the HDR-PJ260E, or the HDR-CX260V both from Sony which and both of have better reviews.
If you want a larger display diagonal then you might want to look at the Canon Legria HF S30 (3.5") which also has a higher rating.
What does "display diagonal" mean?