Personally, I hate any contracts over 4 years...but....this really was a special case. Ottawa needed a big signing desperately. We need this commitment to the fans, to our core players, and to the city (especially when starting to talk about a new arena in 10+ years).
I am worried about any potential long term health effects and all that as well. But having the contract end at age 34 is a really good thing for us. If the team is contending in a few years, we have the luxury to hang onto him for the whole 8 years, even if he does decline.
If things aren't working out too well, we can start shopping him when he's 31-32 or so, and get a nice return. 2 years left on the deal, and at that age he will probably still be at the plateau (likely a year away from a decline) so his numbers should be good, and goal-scorers are always in demand (hell, if teams still want a broken down Heatley, Ryan should be gold).
We should come out of this in great shape either way.