The Hobbit: The Desolation of Smaug is superior to the first film in almost every sense. The second film ups the action, increases the tension, fixes the pacing problems and features a stupendous dragon. I'm a massive fan of The Lord of the Rings and absolutely loved the first film although it wasn't on the same scale as Lord of the Rings. This film it goes back to being as good as LOTR while keeping it's own unique and original style… and a dragon.
Smaug the Dragon is one of the best CGI creations in many years. If you were impressed with some of the creatures from Lord of the Rings such as the Balrog then you're in for a show. Smaug was an amazing special effects achievement that looks absolutely astonishing. Some people were hesitant because he was shown in the trailer, but the trailer shows nothing of what he looks like and is capable of. Plus he's in the film for a whole lot more then you would presume. He was truly terrifying and got my heart racing essentially the whole time he was on screen. A marvel to look at that's voiced by the always perfect Benedict Cumberbatch.
The violence in the film sometimes pushes the limit of a film with an M classification. Please note that this point is far from being a negative thing. There were plenty of scenes in the film with intense and bloody violence including severing of limbs and decapitations of vicious human like creatures. These make for epic action sequences that were so much fun to watch, the barrel sequence being a highlight, filled with gruesome killings.
The film fixes the pacing problems that the first film had and adds in more action scenes. I'm not sure if I mentioned this in my review of the first film as I was so overwhelmed from the film, but it was a bit slow to start of with. This wasn't an overly massive negative as Lord of the Rings had this problem too, but it did effect the overall film. The Desolation of Smaug fixes these problems by getting started into the action right from the start of the film. Plenty of these action sequences were just amazing to watch. They were truly awesome.
To sum up The Hobbit: The Desolation of Smaug beats the original in every sense. Smaug was a stupendous CGI creature, the gruesome violence brought epic action sequences and the pacing problems have been fixed.