In terms of on the court potential, this doesn't worry me at all. At best, it'll be a lateral move for the Cavs. Could backfire.
That being said, while the Cavs haven't figured out how to win an actual NBA title on the court, 2010 will be their 2nd straight NBA Media Championship, to go along with the 2009 title that everyone gave them back in February when KG went down and they were pummeling Memphis and Sacramento by 40 at home and playing air guitar on the sidelines. "Shaq to the Cavs" sounds great to sports morons like Stuart Scott, Michael Wilbon, Tony Kornheiser, etc.
Because of that, my worry is that as much as the media and officials catered to LeBron and the Cavs this past season, that could be increased exponentially with the attention/exposure surrounding Shaq's arrival. And because the players know that, you could also see some FA's take salary cuts in order to go to Cleveland. A front court of LeBron, Rasheed and Shaq would be tough. Hell, at this point, I wouldn't be surprised to see the Suns trade Steve Nash to the Cavs for a case of lukewarm Beast Light. So I guess what I'm trying to say is that, because of the morons at ESPN, perception truly is reality in the NBA, and that may make this a great move for the Cavs.
Also, Steve Kerr is a complete joke. What a garbage GM. He has no business having a job. He didn't even get a first round pick or any prospects out of this. I highly doubt that was the best he could get in return for Shaq. I would be pretty ****ed if I was a Suns fan. Like someone said above, this reminds me a lot of the Gasol trade.