As I play quite defensive with 5-3-2 formation and I often find myself in a 0:0 situation in the 70th minute, I am really happy to have Forrest on the bench. As soon as he is on the pitch as ST, it is easy to get the ball back around midfield. With the 99 balance/98 agility and 95 pace overall, you play him like you are driving a sport car. Super quick, super agile :) With Deadeye, he makes some good runs when triggered on the right time, so you can simply him a long pass. With the defenders already tired, you'll find yourself in 1v1 very often in late game. Big con is his (or my) composure. He misses 2 out of 10 shots. Very annoying if you need to get a goal.
In conclusion, with this card, you should score at least a goal per game.
Positioning (with deadeye)
Skill (not needed for counter play when you pace away^^)