Overall, I'm fairly disappointed with the card, and while I'm still somewhat looking forward to the show, I'm not as excited as I normally am.
Brock/Reigns; not the match I wanted. I don't think it will be terrible, but it's predictable, I don't buy into the story, nor do I expect the crowd to do so. Having said that, if the crowd shits all over it, it could actually be really perversely entertaining...
Triple H/Sting; it has the novelty/big name factor, and I understand why people are excited for it, but I think this match will be pretty poor. I remember watching Sting main-event Bound for Glory 2009(?) against AJ Styles, one of the greatest wrestlers in the world, and the match being extremely underwhelming. I suspect that he's only gotten worse in the ring since then. Also, the Scorpion Death Drop is such a weak finisher, I struggle to take it seriously. I hope they prove me wrong, but I predict that this will disappoint a lot of people.
Bray/Taker; I'm enjoying Bray's segments, and the lack of Taker on Raw should make it extra exciting to see him return at WM. As a spectacle, it should be cool, and I'm looking forward to it. As a match? I think this has potential both to be a massive flop and an all-time classic, depending on which Taker shows up. Wyatt has the ability to tell a really good story in the ring (Cena WM30), but when he has a bad match, it can be really bad (Kane SS13). I'm hopeful this will pleasantly surprise a lot of people, though.
Cena/Rusev; I enjoyed the first match, though it suffered from a largely apathetic crowd. The end result is predictable and horribly overdone (Cena triumphing over the odds), and I'm hoping Rusev doesn't look like a total loser at the end of this, but if this match has the right stipulation (No DQ) it should be a good one. A Submission match between these two could lead to a snoozefest though, and an I-Quit match would probably be even worse.
Rollins/Orton; slow-build, but this will hopefully lead to an excellent, fast-paced match (think Orton/Christian, Over the Limit 2012), and my pick for MOTN. Genuinely excited for this.
IC Ladder Match; Bryan deserves way more, and a match vs Lesnar could have been an all-time classic. Ziggler also deserved a bigger match. However, this should be great, and whilst that doesn't take away my disappointment with the WWE's booking, it does give me one more match to look forward to than I was expecting a week or two ago.
Andre Battle Royal: list of participants looks weaker than last year, I would rather have this on the pre-show and add Stardust vs Goldust and/or a Tag Team Championships match to the main card
The card for WM31 is solid but unspectacular. It isn't as exciting as it ought to have been, but it is unlikely to be a total disaster.