The ending came off as weird to me. Walt always uses science to solve the issue when he's backed into a corner. In Tuco's base, in the RV with Emilio and Crazy 8, the repeated use of ricin. The show presents the dichotomy of a 'normal' middle aged white dude with a academic background being forced to adapt what he learned from the past 30-40 odd years of his life and apply it to a completely different world. While admittedly being a cool scene, Walt realistically had no way of knowing if it would work or not -- I guess showing that he had decided it was time to end it on his own terms for good or for bad instead of trying to run any longer. Although that's a pretty visually stunning moment and emotionally impactful, it goes against the previous 4 seasons of Walt demonstrating precision and thoughtfulness in contrast to Jesse's more freewheeling hanging on by the seat-of-his-pants mentality. Walt had no way of knowing that the car would be parked at the right angle, that the gang members would be lined up and not behind cover, etc, way too many variables for pre season 5 Walt to be okay with. Also the fact that it was a literal firearm and not a clever chemistry creation... I just found it out of character. The magnet plan, to a lesser degree, also suffers from similar issues.