Forest are still unbeaten in the league this year, in the top half of the PL form table (five points behind Arsenal at the top), and a fellow semi-finalist in the Carabao. They may have not put much up in that game, but I wouldn't call Forest an abject team. There's so much context goes missing in these posts. We've won three matches since then, and Forest was only his third league match (not counting Liverpool - who, by the way, I wish we had played a month later).
On another note, related to other posts by many in the past and not aimed at you at all, six weeks training with a new team means very little when you haven't been able to play an actual league match with them. People are talking about that period as if it is a travesty what he's done - but he could have six months training with them, and it wouldn't make a jot of difference until he starts playing games. Plans and ideas are brilliant, but mean nothing until you've had a chance to put them into practice. Like Mike Tyson said, everyone has a plan until they get punched in the mouth. I just don't think the six weeks training should even be in the equation when you basically haven't experienced your team in a game before. Qatar had a six-month training camp pre-World Cup, and they were the worst team the tournament has ever seen. They were looking better by match 3. Matches are the only way you can genuinely learn about your team, and he needed a few before he was able to make some progress.