Brainz.org lists the top 7 reasons why Super Bowl XLIII was an instant classic:

7. Arizona’s Three Goal Line Stands
Who would’ve thought Arizona would have three goal line stands? Granted, Pittsburgh’s short yardage running game is subpar but Arizona’s run defense was mediocre in the regular season…

6. Controversial Officiating
I already talked about Roethlisberger’s near touchdown. There were other close plays that will be debated by sports fans for years to come…

5. Two Great QB Performances from Possible Hall of Famers
Neither team could run, so they had to go with the pass. This could’ve been an ugly game if the quarterbacks threw too many incompletions but both Warner and Roethlisberger came to play…

4. The Longest Play in Super Bowl History
The Cardinals were one yard from paydirt with 18 seconds left in the first half. They had no timeouts but it was first down. They could’ve taken a couple shots in the end zone. However, they only got one play because Harrison stepped in front of a Warner pass and returned it 100 yards for a touchdown. Until this play, Warner was 15 for 16 with five touchdowns in the red zone for the 2009 playoffs…

3. Fitzgerald’s Insane Second Half
Fitzgerald proved that you can’t keep a good man down. His only reception in the first half was in the two minute warning. But in the second half, he exploded with 6 receptions, 112 yards, and 2 touchdowns…

2. The Greatest Super Bowl Comeback Ever… Almost
The greatest comeback was in Super Bowl XXII. The Washington Redskins trailed the Denver Broncos 10-0 at the start of the second quarter, but scored 35 unanswered points to put the game away…

1. Big Ben Does His Best Joe Montana Imitation
…you can’t have an instant classic Super Bowl game without a late game winning drive. (Okay, there’s the Titans vs Rams game but that’s the exception.)…

The article goes into more detail explaining every reason, so make sure to check out the link above to view the entire piece.

The reasons listed above are pretty compelling. Yes, Super Bowl XLIII had several great moments (Harrison’s interception, Fitzgerald’s big play, Holmes’ TD catch). But for me, the game was sloppy on a whole, uneventful in the first half outside of Harrison’s touchdown, and often controversial at times. I thought it was one of the greatest fourth quarters of any Super Bowl played, but not one of the greatest games.

If you want to be technical, I think Brainz.org is right – it was an instant classic. But so many people are coining XLIII the best Super Bowl ever played and I don’t think it even tops two other Bowls in the same decade (Super Bowl XLII between the Giants and Patriots and Super Bowl XXXXVIII between the Panthers and Patriots).