Arsenal can be quite unpredictable in the Champions League. As they are playing at Emirates, I still think they are one step ahead in this match but we will see... It is a really busy calendar for teams playing in competitions like this at the same time. It isn't easy to handle it with the same starting eleven all the time. Rotation is extra important this season as there are more European matches to be played than before.
PSG are on a top form even more than Arsenal and Arsenal hasn't been very consistent in the champions league therefore I don't think this is going to be a one sided match that'll favour only Arsenal. Both clubs are playing good football and they'll both have their chances to win the game. I think the club that wants it more is going to win and since this is the begining of the season and Arsenal will be playing at home, they're going to win. Head to head, Arsenal has the advantage over PSG. I also think there might be a draw somewhere between the both clubs as no one will want the other to win. There's more pressure on Arsenal to win though.