Congratulations to Federer on an extraordinary 17th Slam title. The forehand, his physical shape, the variety of his shots, his serve are all putative qualities of Federer, but if we take into account the 2009 final along with this one, the comparative analysis posits a little talked about aspect of Federer: his intelligence on the court.
In 2009, he began the match agggressive and was not successful (and Roddick did hit some formidable passing shots), thus lost the first set. Then, he adjusted his game, and went to a defensive format, making the match longer and longer, with plenty of off-speed shots, resulting in longer rallies. He was able to come back and win.
Today, Murray began the first set extremely aggressive, and Federer began with an unusual amount of errors (including after he survived the initial break and came back on serve). He lost the set. To circumvent the problem, he did the reverse of what he did in 2009, and began playing a much more aggressive game, looking to cut the points short. Although he was not the better player in the second set (imo - others may differ), he did what was working best for him: build the points around coming to the net. He came to the net
26 times in the second set (vs. 15 in the first) and won twice more points up there (total: 22) then in the first. Building up on that, he began chipping and charging and coming to the net on returns even more in the third set, in which he was the better player. In the fourth set he came to the net 16 times and won 14!
It's one thing to have the ability to insert variety in your game (there are other players who can do that too) and it's another thing to be able to combine the intelligence with that ability in order to have a "Plan A" to fall back to in case your "other Plan A" does not function well. I believe this ability to have more than one Plan A, along with the presence of mind to know when to shift from one Plan A to the next at will, is not tangential to Federer's success: it's one of its primordial elements. While other players strive during their whole careers to build up a defensive or offensive game to match the opposite, and build their weaker shots to complement it, Federer has gone past that stage early in his career, and has excelled in the next stage, the one that other players, for the most part, don't even get to experience.