The Algeria Under-23 international is due to arrive on Tuesday from Panionios and could even make his debut in the Scottish Communities League Cup against Dundee later in the evening.
The Aberdeen boss is confident the 22-year-old will excite the fans with his goalscoring ability.
Brown said: "I genuinely think that our strikers at the moment should excite the fans.
"Vernon is an exciting player when he goes through on goal and when a cross comes in you expect Scott Vernon to be there or thereabouts.
"Josh, we all know how the fans can be lifted when he gets possession. Darren Mackie works tirelessly and is an exciting player.
"But I think Chalali is slightly different because he's more disposed to taking a man on and beat him on the ground, and does the kind of job that Maguire did here, which was mainly creation.
"But I think on the evidence we have seen of Mohamed Chalali, he'll score as well as create so we are optimistic about that signing."