One comparison involves the combined age of the two opponents: Are Anand and Gelfand the oldest players to have contested a World Championship? One analysis concluded Anand vs. Gelfand world chess championship 2012 oldest pair of contenders since 1886. If I were doing this, I would calculate age in terms of years, months, and days at the start of the match, but since I'm not going to do this, it's a moot point.
Another comparison involves the dullness of the match. This was a common complaint during the first six games, which were all draws. It disappeared after the seventh and eighth games, which were both decisive. The same sort of complaints were heard regarding the 2011 Candidates Event at Kazan, Russia. I'm afraid it's just a characteristic of top-level chess in the early 21st century and is not going to change unless some sort of a major change to the rules is allowed. Most of the complainers seem to think it's the fault of the players, a point of view I don't agree with.
The comparisons between the 1963 and 2012 matches prompted me to open a couple of books on the earlier match. This is always a speculative act, because it invariably gets me started on researching aspects which have nothing to do with the original question. A real gold mine was 'Botvinnik - Petrosian : The 1963 World Chess Championship Match', published in 2010 by New in Chess. Although the author is listed as Mikhail Botvinnik, the book is in fact compiled from various sources related to the match. For example, the book has a section titles 'Petrosian's view of the match'. It starts, 'I never thought that I would play a match for the world championship' and then crams all sorts of informed opinion into its ten pages. Following are two excerpts. The first is about the infamous rematch clause.
A convincing victory over Botvinnik in their second match in 1957 made Smyslov the seventh World Champion. The balance of forces in the world chess elite seemed to leave no doubt that chess had a new leader, who was capable of remaining at the top for a long time to come. But there was one obstacle, namely the ex-champions right to a return match. Admittedly, the logic or appropriateness of the return match is highly debatable, since it is really just a further barrier in the path of the challenger.
Judge for yourself -- he has to be successful in events of various calibre, win the formal right to a match with the World Champion, by winning the Candidates' tournament, beat the champion, and then... within a year, he has to meet the ex-champion again. Isn't it all a bit much? It is hard to accept Botvinnik's argument that this lengthy, multi-stage system of qualifying events, followed by a World Championship match itself, could result in the chess world ending up with a 'fluke' champion. If that is so, then the entire system of determining the challenger is at fault. (p.92)
The second is about Botvinnik's intention to play the 1963 match.
It was well known that when he emerged from the Polytechnic Museum, after beating Tal in the return match, Botvinnik had said something to the effect that, if a Soviet player won the Candidates' event, he might decide not to defend his title. Under the rules of the International Chess Federation, the conditions for the World Championship match must be ratified by the FIDE President, not less than four months before the start of the match. Given that matches in Moscow usually begin around the middle of March, Botvinnik still had quite a long time in which to consider whether to defend his title.
There were some outward signs that the chess federation of the USSR was preparing for the possibility of Botvinnik refusing to play the match. This explained the hastily arranged match between grandmasters Keres and Geller, who had shared 2nd-3rd places in the Candidates' tournament. The match was needed to determine outright 2nd place, the player concerned thereby gaining the right to play the next Candidates' tournament, but also, what is more important, the right to participate in a match for the World Championship itself, if Botvinnik did not play. (p.93)
Although it doesn't say so explicitly, that second is likely related to the first. Botvinnik hesitated to play because his right to a return match had been taken away by FIDE. It's a fact that he never won a match in defense of his title.
A couple of resources worth visiting and revisiting are:-
- Chessgames.com: Anand vs Gelfand, 2012, much discussion plus links to individual games.
- Chessbase.com: World Championship Moscow, an index of links to individual articles.
I haven't spent nearly as much time with these as I would like to.