Well, there's just not that many games that are like it really, its part Moba, part FPS, part class based shooter. I know there were a few games in the past that did similar things but lacked the polish and wider range of skills. Its an FPS and draws inspiration from TF2 but really besides similar game modes it feels and plays very different to TF2.
Most of the depth comes from the characters themselves each with specific movement mechanics, skills and ultimates. The counter picking, the use of the map for strategic advantage, knowing cooldowns on abilities, knowing positioning, causing distractions, divide and conquer tactics, co-ordinating ults, etc. You got 24 characters all with incredibly varied skills and some of them synergize well together, knowing which character to pick in very specific situations is key in this game.
Eg, sometimes nothing is going on with my team on offense so I flank with Genji and die but my team get picks because I caused a distraction in a strategic time and place and caused the enemy to focus on me giving my team a chance to break through their defenses. This is the strategic part of the game, for every situation and team comp requires strategy in terms of knowing the situation, : eg: I;m defending payload at the last point as soldier and my team is having trouble holding defense so I switch to Reaper because his high damage up close, I know the enemy team will be close to the payload.
Its a thinking mans FPS with a high ceiling for those with mechanical skills as well (Mcree, Genji) which is refreshing in this age of military/mech shooters. BTW not trying to sound elitist but I play this game on PC and never tried the console version, but I think this game is more suited for PC controls so I understand if some console players would dislike this game since it was designed and balanced for PC version, I'm speaking primarily about the PC version here.