I don't hate Roman Reigns. Seriously, I don't. He's a perfectly competent wrestler and I've nothing against the man.
That having been said, if they're feeding him the Undertaker's retirement match, worse yet if Reigns wins, I will burn England to the ground (to paraphrase Adam Blampied). The problem is that you know that if this is 'Taker's last match he's going out on his back. He is the oldest of the old school and he is not going out on a win. No matter that not a wrestling fan in the world would begrudge him going out on a win. He's the Undertaker, only Hulk Hogan has legitimate claim to being more iconic than this man.
And even if 'Taker has to go out on a loss, why oh why does it have to be Reigns? I don't hate him but the WWE's obsession with selling him as a main eventer is what's burying him with the audience. They had to turn down the audience audio on Reigns/Triple H at the last Wrestlemania because of thunderous audience booing.
Now they're giving him the Undertaker match? Perhaps the final Undertaker match?
If they waste the retirement match of a legend on Reigns I don't think his standing with the audience will ever recover. I think the resentment will follow him forever and that would be sad. I genuinely believe Reigns could get over as a mid-card heel, at least on the evidence of his recent feud with Rusev. That worked, albeit in a funny way where the bookers thought Reigns was the face even though he ruined Rusev and Lana's wedding. Still, he acted like a bad guy and the feud fed off the existing heat he had with the audience.
Now, I don't think any final match will really equal the mythic status that 'Taker's last match should have but throwing it away trying to get a man over out of sheer belligerence is just squandering a unique opportunity.