All this data is potentially out of date, and should be taken with a truckload of salt
Like many Minmatar ships, the Nidhoggur is often overlooked by pilots. Its marginally inferior stats and lack of a damage bonus usually send prospective pilots over to the Thanatos. However the Nidhoggur has several advantages that allow it to fill the carrier niche very nicely. Firstly it is the only carrier to receive a bonus to repair amount making it the premiere choice for fleet repair, a carrier's primary function. Secondly it is substantially cheaper, often running a hundred million isk or more below a Thanatos. This allows Nidhoggur carrier teams to be deployed quickly and in force, where their repair abilities will be much more critical than either their effective hitpoints or damage.
In Norse mythology Nidhoggur is a dragon who eats the roots of the World Tree.
Below are additional ships images. Click the image below for a larger version: