I think this is a great appointment, we can all say what we like about Fat Sam, much of it justified, but, what he will do will make us hard to beat, he will shore up the defence and will play players in there proper positions, and will get the best out of the players he has at his disposal.
Roy had no idea what to do with his players, he never identified a decent way to play and the results against San Marino etc papered over the fact that we couldn't play and get good results against any of the top teams when it mattered i.e. Italy in 2014, Uruguay in 2014, Russia 2016 etc etc
I don't believe he will allow the players to bring there ego's and sponsorship deals etc into the England dressing room, I genuinely think he will treat everyone on there own merits and will give everyone a fair crack of the whip, he is a manager that has been around the Premier League and the Championship for many years, he appears to be well liked by his counterparts despite some of the banter and hopefully he will get the respect of all the players.
The success of this appointment will be dependent on who he has for his backroom staff, will they be his choices, will they be FA choices etc, if he gets free reign that he should do, then he will fall on his sword should he not get the results that are required.
Overall, its a good appointment, good luck to him, I think it will bring a touch of the Terry Venables era back, i.e. a bloke that the public and people within football seem to like, not the 'best' manager but someone who has the potential to get the best out of his players and the selected team.