As its tagline, obviously it's not the same story. And it wouldn't have been this unique and fresh storytelling without the Imtiaz Ali's personal touch.
The short answer to the most important question "is it worth a watch?" is, "heck yeah, it is".
I don't want to elaborate why is this movie worth a watch or how it unfolds step by step or how were the actors, script, editing, music etc... as sometimes it's better to enjoy a movie by gradually becoming a part of it without being known to even a small plot details, without being a harsh critique; which wouldn't be possible if you know even a one review in detail.
You might get few clichÃ©s, slight over the top complex scenes; on a different note there are many scenes and sequences which might stay with you for a long time.
Only one thing I can assure is that you will fall in love with the soundtrack if you are not already.