It's a fair contract, Gallagher paid his dues and more than earned it. You know exactly what you get out of him every single shift, he's as consistent of a player as you can get. This guy only knows one way to play the game and has never taken a single shift off since his WHL Vancouver Giants days. Everyone team in the NHL would welcome a player like him.
He's arguably the best player in the league at scoring goals in high paying zones around the net, tipping shots, pouncing on rebounds etc. He's mastered that art and is like the modern version of Thomas Holmstrom. He also proved that he's one of the most productive players 5on5 in the NHL. Out of his 22 goals last year, he only had one on the powerplay. The reason is simple: Montreal's PP has been terrible, the team had real issues gaining the zone and maintaining puck possession. On a better team, he could have easily been more productive.
About the age factor, look at players like Brad Marchand, he's had and is still having his best years from age 27 to 32. Bergeron is still a very effective veteran at age 35. Not everyone regresses as soon as they hit age 30. Gallagher is 28 and will be signed until age 34. I'm expecting Gallagher to be in the same mold for Montreal when he enters his 30s; a home-grown player, solid veteran and leader that young players can look up to. You want your younger players to play the right way and be surrounded by these type of veterans, who lead by example and give their 110% every single shift.