I think Sandy Alderson was the best possible choice for GM. The Mets needed someone with enough age/experience/reputation to force the Wilpons to take a less active role in the baseball decisions. I don't know if Alderson will have relatively complete autonomy, but he has a much better chance of receiving it than Hahn, Byrnes, or Daniels would have.
It's been a long time since Alderson has been a GM, but all indications are that he'll be a modern, stat-friendly GM. Alderson was ahead of his time - an Ivy League grad without a playing/scouting background who was a GM well before that became a common resume for the position.
But, before we get too excited, I think it's important to realize that the Mets have dug themselves a decent-sized hole, and it won't be so easy to turn around the organization over night. Every other team in the division has at least one legitimate future superstar in his early 20s. In last year's rankings, Baseball America's top 3 prospects in baseball were all from the NL East (Heyward, Strasburg, Stanton). BA's mid-season rankings had the Phillies' Domonic Brown at #1. I assume the Nats' Bryce Harper will be joining him near the top of the list. Prospect expert John Sickels recently said about the Mets: "I am impressed with the depth in C+ guys. What the Mets lack are surefire elite types."
Fortunately, the Mets have more of one thing than any other team in the division: revenue potential. So, while players like Ike Davis and Jon Niese will never be superstars, the Mets can hopefully plug enough positions with these cheap young guys that they can afford to spend big on a few top free agents in the next few years and start contending for real in 2012.
In the short run, I'm pretty pessimistic about the team's chances in 2011, so I'm mostly hoping that Alderson starts spending big on draft picks and young international signings. The Mets need to build a much better farm system.
As for making bold moves, the only valuable trade assets the Mets have that could be dealt for prospects are David Wright and Jose Reyes. I understand it would be a very tough sell to the fan base unless the Mets got an elite young talent back in return for either of those guys. If I was Alderson, I'd seriously explore what the market for Wright and/or Reyes is, but might be hesitant to pull the trigger unless I was blown away by an offer. Trading Reyes makes more sense because he's a free agent at the end of the season. I'm not sure what a realistic return for him would be - Casey Kelly and Daniel Bard from the Red Sox would probably be both too much for the Sox to give up and not enough to please the NY fans.