I've not heard all of Queen's unreleased stuff.
Here is what I think of some of them:
A Dozen Red Roses for My Darling: I don't like it. Just synths and fake drums - 2/10
I Go Crazy - Should have been on The Works. Good riff, authentic drums, catchy vocals and a good feel. Without any doubt it's better than Tear it Up - 8/10
The Call - 2/10 - Don't know much about it. But I don't like it.
Robbery - 7/10 - Definite potential, If Queen had worked on it a bit more, it could have made it onto Innuendo.
Lost Opportunity - 6/10 - A bit patchy but if Queen had worked on it the song would surely be able for a replacement for Delilah.
My Secret Fantasy - 6.5/10 - Interesting mix of styles and experimentation. With more work on the vocals certainly could have replaced Delilah.
Self Made Man - 7/10- Would have fitted in well with the Innuendo album. Brian is a bit quiet though. It reminds me a bit of some of The Cross songs with the funky keyboard riff. I like the guitar bit in the middle with Freddie's tounge in cheek attitude
I Guess We're Falling Out - 7/10 - In my opinion would have been a nice replacement for My Baby Does Me or even Party. It has the right sound and mood. I think Freddie could have done a bit better with the lyrics.
Stealin - 6.5/10- Tounge in cheek, Fun. A style and mood of song Queen had not experimented with. Would have fitted in well with the Miracle.
Hijack My Heart - 7.5/10 - One of the strongest unreleased Queen songs. Good lyrics and Roger's singing is quite nice. Quite a good riff. Should have been on the Miracle.
Dog With a Bone - 5.5/10 - Okay and a bit rough. Quite a good solo though.
Soul Brother - 7/10 - Perfect replacement for Body Language.
A Human Body - 7.5/10 - Replacement for Don't Try Suicide?. Nice song.
I do wounder if these songs will appear as bonus tracks on the 2011 Digital Remasters.