I can't say I agree on the "common" view of Darkthrone having died in the ass after the first four. If anything, while the first four have their place, and provided the foundation for many, I dare say that Culto & Fenriz realised "their job was done" and have been simply enjoying playing music and paying respect to their influences ever since. Infact, their later works flesh out the black metal ideas and almost educate us more on what their true entity of black metal is about.
The move from death to black metal was the best thing they could have done - think of all the bands who would not exist were it not for Darkthrone.
I find it quite upsetting though, that their later works are slagged so much. I feel that up to this very day, Darkthrone are still more grim than almost every other band in the black metal sphere, and they do it just by being themselves and being true to their ideals.
The new album is going to seriously kick some ass if the EP is anything to go by - that second half of Hedninger Fra Helvete is worth buying the EP alone, it clearly shows that not only does Culto still "have it", but he's coming up with better ideas than ever. Their new works may be more heavy metal and punk influenced, but if anything I truly believe that after 15 years Darkthrone are leaps ahead of the pack and really make you realise how fake the pretenders really are.