These are very good requests. A critical appreciation is an analysis of a work that discusses the two kinds of literary devices: literary elements and literary techniques.
- Literary elements are those things that are common to all literature: e.g., tone, point of view, mood, chronology, characters, diction, structure, theme.
- Literary techniques are those tools from among which an author can choose for optional effects: e.g., figures of speech, rhetorical schemes, onomatopoeia, personification, symbolism, imagery, simile, metaphor, metonymy, idiom, etc.
A critical appreciation will select the most interesting or most relevant of each category--elements and techniques--and discuss their form, significance to the work and effect upon the reader. Thus, the critical appreciation will give a detailed, though limited, view of the work that illuminates its literary devices and merits.
To begin you on the right track of a critical appreciation for As You Like It, it is a Shakespearean comedy, in which couples wind up happily married, that follows Sidney's mimetic principles (i.e., imitation of divine principles in order to instruct) of examining all types of a thing (love) in order to reveal truth about that thing: in this case, the thing being examined in all its possible manifestations is love.
The play is written in verse and prose. When in verse, it is iambic pentameter. Contrary to habit, principal characters may speak in either metrical or prose lines. An example is the conversation between Rosalind and Celia (it is interesting to note that Duke Senior never speaks in prose; do other male principals speak in prose or just the female principals?):
Let us sit and mock the good housewife Fortune from
her wheel, that her gifts may henceforth be bestowed equally.
I would we could do so, for her benefits are
mightily misplaced, and the bountiful blind woman
doth most mistake in her gifts to women.
Imagery and metaphor are very significant techniques used. A good example of imagery is Duke Senior's tribute to the nurturing truths of nature. He says through imagery that nature is an honest councilor and shows what the Duke truly is, which is unlike the perilous envious councilors of the court who flatter to reach their own unjust ends:
... I shrink with cold, I smile and say
'This is no flattery: these are counsellors
That feelingly persuade me what I am.'
Jaques' speech about growing old borrows a metaphor from Duke Senior's remark about the world being a "universal theater / ... / Wherein we play in." Jaques famously extends the metaphor to the seven acts of a play being the seven stages of life, ending with "mere oblivion."
And one man in his time plays many parts,
His acts being seven ages.
Irony and plays on words are central to anything that Touchstone utters. You can examine his conversation with Corin about the shepherd's life to find examples of irony and word play in Act III scene ii.
Now, in respect it
is in the fields, it pleaseth me well; but in
respect it is not in the court, it is tedious. (III.ii)