I am traveling from the Netherlands to Italy but I don't have credit card, only a debit card (Maestro) ING. Does it work everywhere (hotels, restaurants, trains, cafes, museums ..) or are there any restrictions?
Yes, from my experience, all Dutch debit cards perfectly work in Italy. The only one possible exception are hotels since they quite often require credit card presence when you check in.
In any case of issues, you can go to any bank office and take cash as much you needed. And order an credit card from ING since it is handy in exceptional cases and buying online
I have a Maestro debit card issued by an Italian bank. It works without a glitch both in Italy as well as abroad. For completeness sake, note that when paying by card in Italy, the cashier will ask you whether you want to pay by credit or debit card by saying "carta o bancomat?". Carta means credit card and bancomat is debit card.