Ulver's sound progresses here even more than on previous records. The music is influenced by several different genres such as rock, jazz, classical music, industrial music, and electronica.^[4]

The working title of the album was Utopian Enterprise, then changed to Heart, before the band settled on Blood Inside.^[5] Speaking about the evolution of the album, Kristoffer Rygg commented, "Utopian Enterprises is a title we all like and it goes back to Perdition City and some ideas stemming from that period, but as the lyrics took form it did not fit anymore. Then there was the Heart Album. Even we thought that was a bit pretentious. So Jørn and I are walking/talking outside one night trying to figure out what it is all about. Thinking only in key words: heart, blood, red, rose, beauty, violence, body, life, death, ambulance, hospital and so forth. Then it struck us: Blood Inside."^[6]

"In terms of genre, it is more rock than electronica. Even a bit psychedelic and/or progressive at times. The mood is kind of sanctified and sad. It has a few frivolous moments as well, but as they say, 'even in laughter the heart is sorrowful' (Proverbs 14:13.). I know there are many people who expect some kind of sequel to Perdition City. It's not. It's got a different kind of sensibility. It's also got far too much sound on it to be similar to our film soundtracks, which are quite often based on very simple and transparent kind of themes."^[7]

"[Blood Inside is] kind of counteracting the 'less is more' trip we've been on lately. Our last proper album Perdition City was so keen on being cinematic that it almost read as an application form to the film industry. While we did get into the film industry, our illusions of how fun and easy it would be to score motion pictures were downed pretty fast as soon as we got more acquainted with those people and their working methods. Now, having been a somewhat voiceless and underlying stratum in other people's visions for a while, we just felt like we had to put up a big fat wall of sound this time around."^[8]

"Blood Inside is not really that much of an electronic album, but it uses a lot of the technology we learned from our electronica phase. It showed us a different way to make records (while) still following different musical perspectives. They changed all of mine; it's not just true for me, it's true for most people. Blood Inside is like a monster kaleidoscope of illusions, very neatly arranged. As it seems now the next record is going to be without all that covering and more humble, with a more heartbreaking atmosphere; it's not going to be the same at all. We are kind of circular; it's reaction, anti-reaction, reaction, anti-reaction... it plays off each other; that's the way we work. As I said, we're not really good at perfecting a formula or sticking to what we know."^[9]

Rygg, commenting in Unrestrained magazine in 2007, also reflected, "That was a very anarchistic album. We revelled in the freedom of not having to play by anyone's rules, our own included. With the EPs and all the stuff we did before, we had rules. The Silence EPs had rules because they were all based on mishaps. That's the whole concept of glitch music. It has to be based on sounds that aren't intended, in a sense. We also had rules laid out for the soundtracks, naturally, so Blood Inside got a little out of control. We just went all over the whole spectrum. I think it's a solid record but it's very different from what we've done now. I think we made some good music. I think the track "Christmas", for instance, and "Your Call" are good tracks. "Your Call" was, by the way, a song that influenced this new record [Shadows of the Sun]. It set off the musical tone for this record."^[10]

Scene Point Blank described Blood Inside as "a beautifully crafted album of both substance and style. Certainly, Blood Inside is still not for everyone, but those who choose to indulge in this will find themselves rewarded on every level."^[11]

SputnikMusic commented, "[Blood Inside] is ambiguous and full of intricate layers and influences working to tell a story that is both haunting and mesmerising. Garm’s beautiful distorted vocals act as outcries of a desperate man hidden, pushed in the background of the story that the instrumentation tells."^[12]

Webzine Avantgarde-metal.com concluded: "the sound of the album is maybe their most extravagant, extrovert, dynamic and wild, ranging from swing band to danceable hard electronic pop, with a lot of peaceful moments in between so much energy."^[13]

Eduardo Rivadavia, writing for AllMusic, commented, "The Norwegians' first non-soundtrack release in many a year also brings about some notable changes. Foremost among them being the decision to abandon some of the stark minimalism that characterized those efforts, so that by comparison, the predominantly synthesizer-wrought compositions on hand here sound positively sumptuous." Concluding, "As one has come to expect from Ulver, the total end result is unfailing eclectic, remarkably inspiring, and never less than a brave step into the depths of the unknown."^[14]

A limited-edition CD (2000 copies) was released in a red velvet box containing a numbered cardboard sleeve. A limited vinyl version was released by Profound Lore Records. 1000 copies were made in six different colors:

• 100 transparent/red splatter
• 100 white/red splatter
• 100 red/black splatter
• 100 red/white two–sided
• 300 white
• 300 red