I say good riddance!
He is yet any professional experience as a manager his only thing that is working for him is that he spent 2 and half years as an assistant manager at Dortmund under Lucien Favre. After that defeat against Stuttgart he should probably have walked out with the manager. I'm afraid that Dortmund is going to lose some of their stars if they see that the team is not headed in the right direction and by then it will be like a sinking ship and everyone will be trying to jum out.
It was a good move by Dortmund's management to hand Favre the termination letter. Dortmund's performance this season has been nothing to write home about both in the domestic Bundesliga matches or in the Champions league which they made it out of the group stage only because they didn't have stronger opponents in group F. It's also too early to start getting worried about how Edin Terzic would fare. We would know in a couple of games but from what I know, he'd be serving as an interim manager till the end of the season.