The 200d is a powerful device, and for small businesses with experience with Windows Storage Server 2003 - and the level of expertise required - it could be an attractive choice. It has an impressive array of features and supported protocols, with performance to match. And the built-in REV removable drive is a nice plus, especially for businesses that like to keep some of their data backed-up and moved off-site.
SOHO and even many SMB NAS appliances are usually inexpensive, quiet, consume little power and have low maintenance requirements. The 200d, on the other-hand, just feels more like a standard Windows server (although in a relatively compact form factor) with a NAS web GUI front-end bolted on.
Which type of NAS is right for you depends, of course, on your requirements. If you need to support a network with an assortment of client OSes, have sophisticated user and group management needs, have Windows server expertise in-house and cost isn't a primary consideration, then the 200d could work for you.
But if you're budget-minded, have a homogeneous network and just want to get additional shared storage onto your LAN and forget about it, then there are many more cost-effective choices available than Iomega's 200d series.