I'm so happy to see people responding positively to Shane's return. I've always liked Shane McMahon. I enjoyed him as a personality, and as a wrestler he's the best of any of the McMahons, could probably have made an actual go of it if he'd had the inclination to fully dedicate himself to it. And I have missed him since he chose to leave, to the point where not often, but occasionally I did think it'd be cool to see him on WWE TV again. So while I could have understood people rolling their eyes at another McMahon saga, I was very happy to hear of his return.
I also think this is a really interesting story they've set up too. With Shane addressing the problems actually facing the company head-on, blurring the line between reality and drama the way the best storylines do, and proposing that he has the means to right the ship (and maybe end the tired heel authority figure shtick for at least a good long time) is a great way to have people invested in him winning. But to then put him against The Undertaker at WrestleMania is a great twist, as it means that for once we are invested in The Undertaker losing at Mania... unthinkable! And so perhaps it's a good thing the streak is over and it's not totally unthinkable that Shane could win. Off the top of my head, my guess is Undertaker destroys him, but something happens to give him a change of heart at the last gasp, and he lies down and lets Shane pin him for the sake of WWE's future, making the heroic sacrifice before walking off into the sunset.
Kudos to WWE for injecting a compelling story into the mix that feels like a genuine spanner in the works no one saw coming.