From a head coaching point of view, I expect the Bills to be better.
Sean McDermott is a workaholic. I think his work ethic is going to rub off on his team in a major way. McDermott is known for being the kind of coach that places a heavy emphasis on attention to detail - the little things that win big games, and discipline.
Rex Ryan was anything but a workaholic. His laziness in preparation, lack of attention to detail and his own lack of self discipline was a major reason why the Bills weren't successful under his "players coach," leadership.
On Offense - I think Rick Dennison is a huge upgrade over Anthony Lynn.
Running the football has never been a problem for the Bills. Lynn did a great job with the run game when he took over as OC, but the Bills passing game ranked 30th last year. The coaching staff had a low risk, low reward mentality that Tryod Taylor had to try and make big plays with.
The Bills passing offense ranked 28th in 2015, 18th in 2014 with Orton, 28th in 2013, and 25th in 2012.
Dennison was OC of the Broncos in 2015 and 2016.
In 2015 the Broncos passing offense ranked 14th with a quarterback on his last legs in Manning, and Brock Osweiler starting 7 games.
In 2016 the Broncos passing offense ranked 22nd with basically a "rookie," QB Trevor Siemian starting for the first time in his 2nd year.
Dennison was the OC of the Texans from 2010 - 2013.
In 2010 the Texans passing offense ranked 4th with Matt Shaub at QB.
In 2011 the Texans passing offense ranked 18th.
In 2012 the Texans passing offense ranked 11th.
In 2013 the Texans passing offense ranked 15th with Matt Shaub and Case Keenum splitting 8 games each.
All that said, I expect the Buffalo Bills to have one of the best passing offenses the team has had in many years come 2017.
Dennison's offensive passing system combined with a great running game and a quarterback with something to prove is enticing.
On Defense - You can't get much worse than Rex Ryan's defense the last 2 years.
Going back to a 4-3 is a dream come true for Marcell Dareus. The Bills run defense ranked 29th last year.
McDermott runs a zone coverage secondary. Rex liked to run man coverage.
McDermott's defense is easy to learn, not complicated and confusing like Rex Ryan's.
Don't think, just play football. Players are going to love that.
I don't think it's a stretch to say that the Bills defense will be better in 2017.
So...
A better coach, a better offense, and a better defense bodes well for Bills fans.
Superbowl! No, but I think the Bills are finally on the right track to get there.