Conclusion

In all likelihood, we'll get a decent match out of Reigns and Lesnar. They pleasantly surprised the world three years ago and Reigns has much more experience under his belt. As for Lesnar, his match-quality has dipped and he has been accused by many of phoning in his performances. Whether Lesnar enters this match motivated to put on a show remains to be seen, especially since his contract his reportedly up following Wrestlemania. The Beast is also thought to be returning to UFC.
As for Reigns, he'll make a better champion than Lesnar by proxy of actually being on Raw week in, week out. There's always a chance that WWE will tweak Roman's character accordingly along the way. Roman Reigns the performer is a good addition to the roster; he's just been cast in the wrong role.
It's just a shame the outcome isn't in doubt.