The two oldest rumours in the world are (a) that there is a God, and (b) that He is good. There will perhaps never be conclusive proof either for or against those postulates, and Dasavatharam does exactly what you've done all your life - stop thinking about it when you hit a dead end.
However, where Kamal Hasan's hyped latest that seems to start off aiming to be a theological opus, fails to deliver, is that it spends as little time on this deeper aspect as you do in your own life on it, and the rest of the movie is meaningless tripe. For what is essentially a thriller, at no stage does the film really grip you. Heck, most of the time you're not even clear why the villian is after him.
Then, that whole 10-role thing seems so pointless - as you probably expected it would be even before the film released. What's the point of Kamal Hasan doing a role when he doesn't look like Kamal Hasan at all? It's not like those roles require great emoting. Kamal Hasan's acting is by nature understated, and when understatement comes from behind a thick mask, it's kinda like being served a dish with a different name and a different taste.
Dasavataram starts off with a prologue about a staunch Vaishnavite priest Govinda Rangarajan (Kamal Hasan) being tortured and killed by a Shaivite king for not turning Shaivite. It's not clear what that has to do with the movie eventually, unless the film is saying that God took revenge many centuries later by sending a tsunami on Tamilnadu. That doesn't appear to be the case, and it isn't clear then what it was all about.
The film moves to 2004 where Govindaraju (Kama Hasan) is a top-ranking scientist developing a biological weapon for the US. He discovers that his boss is trying to sell it for his personal benefit, and runs away with the vial containing the formulation, resulting in an ex-CIA man and now professional assassin Fletcher (Kamal Hasan again) coming after him.
Govindaraju flees to India in a series of unexpected circumstances, landing in Chennai and then interior Tamilnadu, and the vial lands in an idol of Vishnu. He tries to get the idol but has to contend with Lakshmi (Asin), a staunch Krishna devotee who, like the Indian state by then, believes he is a terrorist, won't let him get the vial out of the sacred idol.
The couple have to run around the hinterland escaping from Fletcher, and the movie progresses towards a grand finale where the tsunami of December 2004 hits just as the vial is about to explode.
If you are a normal compassionate human - or heck, human - you have certainly wondered about how God would have allowed 1,20,000 people to die in one night and millions rendered homeless, orphans, without a livelihood, scarred for life. Govindaraju asks exactly the same questions, and Lakshmi gives exactly the same replies as a standard-issue preacher at an ISKCON temple would.
At the end, however, the only aspect of the script that would make this movie worthy of its scale is, alas, relegated to some inadequate and diffident dithering, and the rest, like we said, is tripe. The masks on Kamal Hasan look grotesque, and it all looks like an actor indulging himself in some megalomaniacal grandeur than doing something necessary for a story to be narrated well, for a movie to work best. There was once an ANR movie called Navaratrulu where ANR played 9 different roles, and that was something different for those times, something those audiences would enjoy. How much does the thought of a movie where an actor plays 10 characters excite you now?
The 10-character bit also takes the focus away from the film itself, since you start to think that that is what the movie is all about. Kamal Hasan doesn't have much to do in terms of emoting - these are all mostly simple roles, and in any case, any impressive emoting is hidden under the masks. Asin is as expressive as usual, and so is Mallika Sherawat in a brief role.
Several characters - Punyakoti, the grandmom, and even Avtar Singh - seem shoehorned in, without really being needed for the tale or adding anything to it. The film also shows George Bush as a buffoon, and we're not sure it is even legal to showcase Bush as himself in the movie. Or Manmohan Singh or Karunanidhi. The film has only 2-3 songs (thankfully) that pass muster, especially the end-credit Lokanayaka. The visuals are expectedly tacky since this is a South-Indian film that relies on CGI.
Dasavataram is more hype than substance, lost in its main theme, and pretty lacking in focus. It is mostly for staunch Kamal fans - the rest can wait for, oh, whatever's hitting the marquees next.