I first noticed Strix when I was playing against an enemy player who destroyed our team in a siege match. I noticed he was a sniper (which I assumed didn't exist in the game) and I wanted to try him for myself.
His sniper rifle is pretty powerful but against champions of stronger health bars it won't be an easy "one shot" kill. In most games, I fail almost always with a sniper rifle.
So I found it really hard to get the kills I needed to help my team win matches. Strix certainly works better in siege or onslaught. In team deathmatch, he's really awkward to do much with.
He also has a pistol to switch to in close quarters combat, but it's not very powerful but your only hope against a opponent nearby. I know some players like him a lot, but I wasn't a fan myself.