that Poland is rarely the best choice,
You would like to point out your opinion which more often than not is far from reality.
Working in a call center is not considered valuable experience.
The OP has never said that he is working in a call center. He said BPO. The fact that you immediately think "call center" when being confronted with BPO, shows how little you actually know about the Polish job market. Yet, you are always the first one to give your advice which usually is nothing but nonsense.
do you guys think it is a good idea?
At the moment, you are left with 2000 PLN on your bank account. These 2000 PLN are yours to spend however you like. You do not have any other financial commitments i.e. rent, bills, internet etc. etc.
With the new job, you get approx. 1700 PLN more net but you still have to pay rent, bills etc. After paying rent and all the bills, you will be again left with 2000 PLN but you have start all over in a new company.
I think I know which company you currently work for. I know the apartments they offer their employees are usually of good to high standard. This company also offers you training and development opportunities. Not only internal but also external trainings for example ACCA etc.
You may want to speak to your manager about the possibilities of development before you make your decision. I also know that this company, should you be doing a good job, would most likely make you a new offer (add a few hundred zlotych) if you indicate your intentions to move on.
Financially you would not be better off if you do decide to go for the new job. Perhaps even worse than you are now. I am not sure if it is worth to move for this offer.