Alright, I've listened to the whole thing, here's a quick review:
1. Yo - Some of you probably remember this from the Linkin Park - Monster Energy promotional bit back in 2008, you could download a low quality loop of this song as a ringtone called "Brad's Yo." Pretty basic stuff, simple beat with some piano and synth towards the end. Very plain.
2. Slip - As I said before, musically very different from Hybrid Theory. For that, I'm a fan. Otherwise, very passe. Mike raps aggressively, Chester sings the chorus, yada yada we've heard it plenty of times before. But, the music is fairly unique for a HT demo.
3. Soundtrack - Interesting. The chord progressions and pacing of this song remind me of a purely rock band. Like a band like Switchfoot wrote it. I can see why Mike said they thought the demo was "too poppy." But it's still interesting to hear Linkin Park's take on the basic rock sound. The verses sound nice, an electronic beat with a quick-paced guitar riff and moody piano. Sounds like it was written for MTM.
4. In The End - Not much to say about this, not much different from what we already have at least upon first listen, other than the higher quality of course.
5. Program - Definitely a stand-out. The song is pretty bi-polar in that it contains a soft section (what would be the verses I assume) that have an interesting electronica sound, strings, and a clean-toned guitar riff, and of course the staple chorus section with big guitar chords. The verses sound really nice, I wish the song didn't have the power chords and was finished was just the music from the verses.
6. Bang Three - Not much to say about this either. Strings in the verses are much more noticeable, there's a slight change in the piano during the intro, and the bridge doesn't have the guitar solo.
7. Robot Boy - As I said before, the different vocal parts are more clearly distinguishable, and the lyrics are not nearly as good as they ended up being on the album (except for one or two lines).
8. Broken Foot - Your basic distorted guitar song. Nothing too special about this, if you love jumping around in your room to heavy guitars, you'll love it.
9. Esaul - Same demo we've known about I think, just in higher quality. Good to have.
10. Blue - WOW. This is definitely the most unique of the CD to me. Blue has a, well...blues-y sound to it. Almost jazzy, and grunge-y. Chester's melody is very bluesy. Reminds me a lot of Grey Daze. When you listen to this, you could imagine them playing it at a small bar. VERY different for a Hybrid Theory demo.
All in all, Slip, Soundtrack, Program, and Blue are the most interesting listens. They definitely make me wonder what Linkin Park's earlier music would have sounded like had Warner Bros. not tied their hands creatively.