به نظر من، این کادو برای جشن او خوب است.

Yes. به نظر من is a very common fixed expression meaning in my opinion or to me.

Literally:

• به = to
• نظر = view, opinion
• من = me / my

So it is something like to my view/opinion. In natural English, though, you should understand it as in my opinion.

You can use the same pattern with other pronouns too:

• به نظر تو = in your opinion
• به نظر او = in his/her opinion
• به نظر ما = in our opinion

Because Persian normally follows subject–object–verb order, unlike English, which usually uses subject–verb–object.

So:

• این کادو = this gift
• برای جشن او = for his/her celebration
• خوب است = is good

In English, we say This gift is good for his/her celebration.
In Persian, the verb است usually comes at the end.

That final placement is very normal in Persian.

این کادو means this gift or this present.

Parts:

• این = this
• کادو = gift, present

A useful note: کادو is very common in everyday Persian, but it is a bit less formal than هدیه.
So:

• کادو = everyday/common
• هدیه = a bit more formal or literary

Both are correct, but کادو sounds very natural in daily speech.

برای usually means for.

In this sentence, برای جشن او means for his/her celebration or for his/her party. It shows the purpose or intended use of the gift.

So the idea is:

• this gift is suitable
• for that celebration

In many contexts, برای can also mean:

• for someone
• for doing something
• intended for

Here it is best understood as for the celebration.

جشن او means his/her celebration, his/her party, or the celebration for him/her, depending on context.

Parts:

• جشن = celebration, party, festival
• او = he/she, him/her

Most naturally here, it probably means his/her celebration/party.

A pronunciation note: there is an ezafe connection between the two words, even though it is usually not written. So it is pronounced roughly as:

• jashn-e u

That -e sound links جشن to او.

It can mean either he or she. Persian third-person pronouns do not mark gender.

So:

• او = he / she
• depending on context

This is true for object forms too:

• او را can mean him or her

In modern spoken Persian, people often use اون instead of او in conversation.
So in speech, you might hear:

• برای جشن اون

while او sounds more written or formal.

Persian often uses the ezafe construction instead of a separate word like English of.

In جشن او, the relationship is shown by an unstressed -e sound after جشن:

• jashn-e u

That is the Persian way to connect:

• celebration
  • his/her

But because short vowels are usually not written in normal Persian script, you do not see the -e written.

So even though the spelling is جشن او, you should mentally read it as:

• جشنِ او

Because است is the verb is.

So:

• خوب = good
• خوب است = is good

In formal or written Persian, using است is very normal.
In spoken Persian, people often shorten this:

• خوب است → خوبه

So in everyday speech, the sentence would often sound more like:

• به نظر من این کادو برای جشن او خوبه

Both are related to to be, but in many sentences like this one, است is the more standard written form.

Here:

• خوب است = is good

You may also hear هست, but است is more neutral and standard in writing.

In conversation, both are often reduced or omitted depending on style, but the most natural spoken form here is usually:

• خوبه

So for a learner:

• است = standard written
• خوبه = very common spoken equivalent here

Yes, it is natural and correct, especially in a neutral or written style.

A more conversational version would be:

• به نظر من این کادو برای جشنش خوبه.

Why?

• او often becomes اون or is replaced by the suffix -ش
• است becomes ه
• spoken Persian usually sounds more compact

Also, some speakers might choose a more specific adjective than خوب, such as:

• مناسب است = is suitable
• عالی است = is great

So a very natural alternative could be:

• به نظر من این کادو برای جشن او مناسبه.

That means In my opinion, this gift is suitable for his/her celebration.

The comma marks a pause after the introductory phrase به نظر من.

So it separates:

• به نظر من = in my opinion from
• the main statement

It is helpful in writing, but it is not always mandatory. You may also see the sentence written without the comma:

• به نظر من این کادو برای جشن او خوب است.

Both are fine. The version with the comma just makes the structure a little clearer.