How sprint is implemented in Halo 5 is certainly a more thoughtful approach than previous Halo titles with the feature. However, I do think it could be balanced better with a couple minor tweaks.
1~Increase base player speed by at least 10-15%. I don’t want Halo to move like Doom 3 or anything. But, Halo 5 reminds me of Gears of War in that when I’m not sprinting or thrusting I feel like I’m near immobile. It makes me feel like I have to sprint. This strengthens the need to sprint every where. This -Yoink!- in players last ditch efforts to avoid death. I have to thrust and/or sprint after them, effectively neutralizing combat.
A positive side effect of the increase would bring back strafing as a legitimate tactic. Currently players move to slow to really disrupt the average BR user.
2~Decrease sprint speed. Sprinting should be more of a way to kind of “hurry up” a bit. Not a full on sprint. This would decrease the likely hood of a player thruster running away (thruster to cover/sprint away). Getting to that next land mark would decrease a bit.
Overall the defensive capabilities of sprint still feel to strong. I would, at the very least, like to see robust custom game options on the level of Halo 3 or Reach. Adjusting base player speed is nice. Adjusting sprint seems like a natural evolutionary step.