Pros:
1. You can connect a normal telephone and make phone calls through the inserted 3G SIM. Data and voice work together.
2. Internet fail-over system (not seemless though). In the WAN setup you an specify a pingable ip address in the internet; if that address is not reachable, the router changes over to 3G. Also, when it becomes pingable it switches back.

Cons:
1. unintuitive interface. Many things mentioned in the manual is not found in the web interface (e.g.: routing mode - bridge vs ...

device is very unstable and keep on disconnecting didn't expected this from D'link

It is working as per my expectations, it has got good wifi connectivity....
But the built quality is not great...Boot time is little more...
Not available else where other than Flipkart...:) Got it the next day through One day delivery service....

The router DWR 512 did not work. Took it to the Dlink service center in Nehru Place, Delhi. They tried putting in various SIM cards but the router would not connect. It has been a waste of money.