In Google Mail there are more than one forwarding rules allowed, what is very necessary.
Defining a 2nd forwarding rule is denied:
I like the idea of Outlook.com: hopes and opportunities
I think it is also necessary to be able to change the position (chronological order) of forwarding rules or rules setting a category, which unfortunately is not possible at Google Mail also. If one rule sets a category and another later operated rule has a category as precondition, it is very necessary to be able to change the position of rules.
Without this features, the rules become very complicated, because you cannot subdivide the rule-tasks to more different-rules by using categories, defined by pre-operated rules.
I hope that Outlook.com will not have this big disadvantage of GMail, if it will be out of the beta-stage.
It seems that Outlook.com has many of the big advantages of Gmail (send from other addresses), it would be fine if Outlook.com could provide the biggest advantage of Yahoo-Mail, the 500 throw-away-addresses. If the first characters of the throw-away-addresses could be choosed more freely, Outlook.com could become the greatest email-service.