Nothing more, really.
We know from GP2 that he is a decent driver on the wet, able to do some good performances.
And today he have done an OK race, just confirming to me that the Williams is really good this year. Much better than the Force India and Torro Rosso.
But if you think that Maldonado was able to be ahead of Kimi before the red flag, and that he dropped to the back after the restart (he miss is pit !!), you shouldn't be too impressed by Senna.
Just look at the pace of Maldonado on slicks towards the end of the race when he had clean air (lap 41/42/43) :
http://en.mclarenf-1.com/index.php?page ... no%20Senna