Generally speaking text on LCD screen will be pretty sharp as long as you use native resolution. Lowering the resolution will increase the size of the text, but will also make it a bit fuzzy due to interpolation. The lower the resolution from native, the less sharp it will be. Some monitors do have a sharpness adjustment in the onscreen menu if you use less than native resolution.
The ease of reading text on a 1920 x 1080 resolution monitor depends on the size of the monitor (or HDTV) and how far you are sitting away from it. The text on a 27" monitor with 1920 x 1080 resolution would be larger than on a 22" monitor with 1920 x 1080 resolution. It also depends on your vision.