Unlike the iPhone, the Storm does feature MMS and video recording, but there's no video calling, since the device doesn't have a front mounted camera. Of course most iPhone users will insist that they don't need MMS and video recording - as always, it comes down to personal need and preference.
But as with all BlackBerry devices, it's the mobile email integration that's a, if not the key feature. RIM has been doing push email for so long now, that the BlackBerry is pretty much synonymous with email in your pocket. The Storm is just as good as any other BlackBerry at accessing your email, and in some ways better. The obvious advantage is the big screen, that makes it easy to read longer emails. But RIM has also integrated the Storm's multi-touch support into the email client, so when you've finished reading one email, you can simply swipe the screen to switch to the next one. Obviously the Storm has full Exchange support through the BlackBerry Enterprise Solution, but if you don't have corporate Exchange setup, it's simple to add multiple standard email accounts to the Storm.
The Documents To Go suite comes pre-installed on the Storm, but you can't create new documents, you can only view and edit existing documents. You'll need to buy the Premium version if you want to create new documents. However, all you really need to do is copy template documents to the Storm, then just edit them and save them under a different name whenever you need to create a new document.
Hardware wise, this is a quad-band handset so it should work pretty much anywhere in the world, including difficult locations like Japan. From a data perspective the Storm can handle full 7.2mbps HSDPA, along with UMTS, Edge and GPRS, so you should be able to get at least some kind of data service no matter where you are. There's 1GB of storage built into the Storm, but it does sport a microSD card slot, so you can expand that storage easily and cheaply - it only costs around £16 for an 8GB microSD card.
One of the strongest selling points of BlackBerry handsets has always been long battery life, but unfortunately this isn't carried over into the Storm. RIM quotes 15 days standby time, but in reality the Storm gets nowhere near that. If you have any intention of actually using the Storm as a data device and a phone, you're going to have to charge it every night. And even leaving the device purely on standby, without really interacting with it, I couldn't get more than two or three days before the battery went dead. That said, I'm not one to bleat on about having to charge a phone every day, since I tend to charge my phone overnight as a matter of course, it's simply not that much of a hardship. The annoyance comes when you have to go away for a few days and you're hoping that you don't have to take a phone charger with you - in the case of the Storm, take the charger with you.