1. My new friends are all great.

2. All my new friends are great.
2-2. All of my new friends are great.
3. My new friends all are great.
4. They all are great.
5. All of them are great.

(Are they all grammatical?
What is the part of speech of 'all' in Sentence? In the sentences from Sentence 2 through Sentence 5, 'all' is a pronoun, isn't it? )

Hi Mr. John,

I am not a language expert, but would like to comment on your query.

I feel 3 and 4 are incorrect. Or at least they sound so. To me, 2-2 and 5 sound gramatically perfect, while 1 and 2 sound ok, but too casual.

Hope this helps

All are correct, but 3 and 4 contain unusual word order.

"All" can be used either as an adjective or a pronoun, depending on the sentence: http://www.answers.com/all

In sentences 1, 2, 3, and 4, it's serving as an adjective. In 2-2 and 5, it's serving as a pronoun.

Yes, all the sentences you provided are grammatical and can be understood to convey the same meaning.

In sentence 1, "all" functions as a determiner modifying the noun "friends". Determiners are words that come before nouns to provide more specific information, such as quantity or possession.

In sentences 2, 2-2, 3, 4, and 5, "all" is functioning as a pronoun. Pronouns are used to replace nouns to avoid repetitive use or to refer back to previously mentioned nouns. In these sentences, "all" is replacing the noun "friends".