The biggest draw is that just about every gameplay mechanic and play type has a counter if you know what you are doing. When you've got two people going against each other who understand how the plays they are each calling work, who know their opponent's play calling and personnel deployment tendencies, and are good on the sticks (especially pre-snap; in particular, individual player defensive pre-snap adjustments are stupid hard to get the hang of), it's a blast. I've had more fun playing Madden in head-to-head games against my friends the past two years than I have in basically any other sports game I've ever played. It's an exhausting chess match.
Don't get me wrong, though, there's some stuff in the single-player experience that still needs work, which is why I made sure I put the emphasis on head-to-head. Not even leaving the field, for example, the CPU AI needs a lot of love and it needs to use the complete toolset provided to users in head-to-head play. One particularly egregious example: one user in my online franchise led the league in rushing with Joe Flacco because the CPU never attempts to use QB Spy / QB Contain pre-snap adjustments
unless those adjustments are baked into the play call. Never mind that scrambling that much is sharp cheddar, the CPU opponent needs to react to a user repeatedly scrambling with a quarterback just as a user opponent would, rather than just give up 10 yards helplessly time after time.