IMO, no. I don't have one and probably never will, it makes no sense to me for the price. If I received a $500 chess gift card from a genie in a lamp, I still wouldn't, I would be willing to pay $30 for it.
Monroi

But you see i dont remember to take notation on some moves and sometimes i write white's moves on blacks

I used to think the chronos clocks were the uber-scams of the chess equipment world, but the Monroi beats it by a mile.
1. Get exclusive rights for use by leveraging off the "secure/safe/unhackable" packaging it presents.
2. Offer really nothing beyond an early 2000's PDA.
3. Charge arm + leg.
4. Profit!
The only thing missing in this story is for Apple to buy Monroi and stick an i in front of it.

The only thing missing in this story is for Apple to buy Monroi and stick an i in front of it.
The price will go down when Apple comes out with their competing product - iChess.

But you see i dont remember to take notation on some moves and sometimes i write white's moves on blacks
Happens to me as well. Of course, there are rituals you should get into to help you:
1. Practice notation as much as possible. Write down friendly games at the club, and if you have time, at rapid events where notation is not required. Practice makes perfect.
Bonus: You will be able to analyze all of your games, and therefore your play will improve.
2. After your opponent makes a move, write it down immediately. Don't ponder over it until you've got it written down. Even if your opponent plays quickly, write it down move-by-move. Moving before you've got his move down only loses time in the long run: you struggle to remember what to write.
Bonus: Forcing yourself not to blitz in serious games will reduce blunders.
Following these simple steps will be better than a MonRoi. They cost $300 dollars! You can get a lot more chess equipment for that, and as you study those $300 worth of videos, books, lessons, magazines, and puzzles, notation will become a piece of cake for you.

Does the monroi worth what it is priced???
No. Pen and paper is fine. Of course if someone is giving you one then woot!!
Paying that much for something that gets so little use in your life just isn't smart. Pro players use them, but they play every day...
But you see i am bad at notation and my coach cant go over the games because my notation is so bad so what do i do and

But you see i am bad at notation and my coach cant go over the games because my notation is so bad so what do i do and
That doesn't sound right. Unless you are completely bonkers in terms of writing your moves down, any good player/coach can perform a minimum level of error-correction to figure out what move was really played. When I go about deciphering hieroglyphic notation from my earlier tournaments, I notice that the mistakes I make are usually consistent enough (mixing e and d files, mirroring the board, forgetting to explicitly mention which piece was moved in case of a choice, etc.) to make sense out of.

I suggest you buy $300 worth of lessons to notate your own games. Pay a hobo to stand behind you and whack you with a stick every time you write something down wrong.

Indeed. If your notation skills are bad, work on them.
It's just another part of serious chess, which also requires work.

If Mon Roi had some competing products the price would come down. In the meanwhile those who want one will have to pay the piper. MonRoi is nice, but is it $300 nice? Most all those on this forum think not. I might want to have one at some future time. If I am fortunate the price will come down and/or other competing products will be out on the market by then. For now I can wright my own notation.
Does the monroi worth what it is priced???