I love the Indiana Jones movies, even the second one.
I get a lot of heat on this when I say it, but I personally think the franchise should have followed the James Bond method (the good parts). By that I mean Spielberg originally said he wanted to do a Bond flick, and Lucas told him "I have something much better..."
With that in mind, they could have had a movie franchise with a new actor taking the reigns every few years. He's too old now (but really... so is Harrison) but at one time I could have seen Dennis Quaid stepping in, and some people shake their heads at this one, but Brendan Fraiser really showed some Indiana Jones ability and style in the Mummy movies. With the right director, I think he could have pulled it off too after Quaid.
As much as I like Harrison Ford and the Indiana Jones story, his age is making me a little skeptical. At 66 I guess it's all in how they write the story line. Sean Connery was very good in The Rock dispite his age, so if done right, this could be good. Done wrong though, and it could also become a joke like Roger Moore was in the last couple of Bond movies he made.
Right now I'm kind of luke warm about it, but I'll definitely buy it when it comes out on DVD.