These are a common feature of some students' essay writing and are best avoided - at least in the body of the essay. A 'value judgment' is a purely personal - and really quite irrelevant - opinion about an author or the author's work.
An example would be, 'Shakespeare is a truly brilliant writer and this play is fantastic!'. Maybe you can recognise that such a statement is out of place in an essay - not least because it is a statement of the obvious and is rather empty.
Hyperbole is a common part of value judgments. This is when we exaggerate to create an effect using words and phrases such as 'truly brilliant' and 'fantastic'. This is best avoided in essay writing - as are the exclamation marks that usually follow hyperbole!