"When you talk about the Champions League, all the groups are difficult," the Napoli Coach told the club website.
"Our group seems one of the most balanced, certainly not easy, as all the clubs we're facing have experience in the Champions League. I think it will certainly be a great challenge for us."
"Borussia Dortmund are a top level side who were Finalists last season and play good football," continued Benitez.
"We know Arsenal well and played them not long ago in London for the Emirates Cup. They have an excellent Coach and experience on the international scene.
"I had my first European success in Marseille, the UEFA Cup Final with Valencia. It won't be easy there, as the stadium is a fiery atmosphere."
For the big stories and the banter follow us on Twitter: @tribalfootball