Corrections in red; stylistics in blue.
I LOVE YOU, ISTANBUL!
Every soul needs to plunge into a vortex of unforgettable emotions at least once one's life. [1]
That moment when you don't sense anything around you, other than the great pleasure of something. You even do not realise what this feeling is... [2]
Only splendour meets every of your step ... no drawbacks....
That is how I feel myself in my lovely city. [3]
I LOVE YOU, ISTANBUL!
[1] Variants: ... at least once in his life. ... at least once in his or her life. ... at least once in their life.
[2] More common variant: You do not even realise what this feeling is...
[3] When translating "чувствовать себя" into English, do not translate "себя". Examples: I feel wonderful. She feels sad. We feel sick.