The mydlink.com landing page before you log in is not secured and you don't see an HTTPS indication until after you log in. I expect that the login is secured, but the way it is now doesn't provide the assurance it should that your connection is secured at login.
After login, I was confused by FireFox 10's address bar security notifications. I haven't liked FF's hiding of the URL protocol information (http://, https://) and with the mydlink site, FF seemed inconsistent in its indication of the browser security status. After checking with Chrome and IE 8, however, I'm pretty comfortable that your connection is secure while you are on the site itself.
But when you are passed to the device's built-in admin server, as happens when you click the Advanced Settings button on any of D-Link's IP camera Settings pages, your connection is no longer secured. This is because neither the cameras nor the DIR-605L router support HTTPS admin.
I initially was able to connect back to the DCS-942L's admin pages by clicking the Advanced Settings button. But when I tried it later on, all I could get was the screen below. The camera was wirelessly connected to my main router instead of the DIR-605L. But that shouldn't matter since the 605L isn't required for mydlink access to the camera.
DCS-942L failed connection
I hope D-Link plans to add more cloud features to its DIR-605L. Because the set that it has right now, while showing proof of concept, isn't very impressive. The Event Notification setup should be completely automatic with no futzing with SMTP settings required and many more notifications are needed.
The Visited history feature is a good start, but would be better if it could be filtered to show only attempts at viewing blocked sites and viewed at a summary level of access counts per site. And all the router's cloud features should be documented somewhere, especially describing how a device gets into the "Suspect devices" list.
On the camera side, D-Link also has to step up its game by offering still and video storage in its cloud. They could differentiate themselves from newcomers like Dropcam by offering a small amount of video storage for free and charging if you want more.
Among router manufacturers, D-Link has the "cloud router" field to itself right now. But NETGEAR has already announced its intent to develop app-based routers, which are sure to include cloud features. And while Cisco has been characteristically mum about its app/cloud router plans, I can't believe they would sit out the next step in consumer router evolution.
At least if you want to play with the cloud features that D-Link has right now and monitor its progress as it develops more, it won't cost you a bundle. But if you're happy with the router you have and have something else to do with the $50, I'd let D-Link warm up the water more before jumping in.