2. The book is amazing and of great value.

Is #1 same as 'The book is amazing and great value'?

2. It is of help.

Isn't be of + noun is equivalent to an adjective?
"The book is amazing" = The <noun> is <adjective>. (This is correct by itself.)

"The book is amazing and of great value" = The <noun> is <adjective> and [the noun is] <adjective>. (The second adjective is "of great value". This is all correct too.)

The word AND ties the two adjectives together like this: The book is [amazing] AND [of great value]. Each of the bracketed expressions is an adjective. You could rephrase it, with the same meaning, as "The book is amazing and valuable". (Or "amazing and greatly valuable".)

"This book is amazing and great value" is probably not what you want to say.

When something is described as being "great value", this usually means great "value for money", or value in terms of some other quantity - for example, a person who is pleasant to be around could be described as being "great value" because any time you spend with him/her will be enjoyable, so your time is well spent; likewise, any purchase or deal, or any product you could buy, can be described as "great value", which is shorthand for "great value for money", i.e. money well spent; a good deal for the buyer.

This is quite different from the meaning conveyed by "OF great value", which is just an ornate way of saying "greatly (or very) valuable" and has a serious aspect, unlike "great value" which more often appears in advertisements.

It is of help = <pronoun> is <adjective>. "of help" is an adjective and could be replaced by "helpful" or "useful" or "well-suited". The word "help" can be used in several senses, so I'll use "assistance", which is a noun, for the next question.

"be of <noun>" would be a verb because of the word "be". "This hammer might be of assistance" = "<noun> might be <adjective>" = "<noun> might <verb>".

"of <noun>" is an adjective. Maybe that's what you mean? That's what I did in the first line of this paragraph. I replaced "of assistance" with "<adjective". That's how I understand it; I may be wrong.
Hi, KNZ.

Thank you very much for very nicely put explanation!

"of <noun>" is an adjective. Maybe that's what you mean? --> Yes.

I got a little confused because I remember hearing 'be of noun' is an adjective but my sentence include an adjective 'great': ~ and of great value.

It's interesting that if it is rephrased, it is '~ and greatly valuable; both 'great' and 'value' changed their part of speech: from an adjective to an adverb(greatly), and a noun to an adjective(valuable)Emotion: smile

p.s) Could you please contribute to my question "I remember him/his playing the piano " Since you are New Zealander?
Students: We have free audio pronunciation exercises.
You're welcome :-) Yes, often there are many different ways to say the same thing; "of great value" and "greatly valuable" (or "very valuable") are just one example. Although literally they should mean the same thing, often the STYLE of speech is tied to the choice of wording. For me, the phrase "of great value" has a very serious, even awed and reverential tone, as if we're talking about something extremely important. "Very valuable" just means what it says; value may be in terms of importance, monetary value, or general helpfulness. "Good value" to me means something like "worth the investment", whatever you're investing (money, time, etc). "Good value for money" specifically relates to products or services that you could buy.

I'll check out your other question.