Heatley should have more value, but this isn't fantasy-land, there is more to a trade then just the value on each side. What good is it to gain a great player, if the team as a whole suffers?
It doesn't work for the Sharks, who simply can't afford to add such a contract because it costs them more core-players then just the two they are trading. Taking away further core-players leaves them with no depth at all. Some may think that it can work, I'm certainly not one of them. Teams can't win the Cup if they have no depth.
As a fan of both teams I like the deal. Cheechoo would replace Heatley on Ottawa's 1st line while Ehroff gives the Senators another good young d-man. Heatley could return to his 50 goal days with Thornton as his centre.