the background seems too dark but that may just be my screen

I quite like it and I definitely prefer the 1st one with out the 'depth effect'.
I would maybe consider shortening the arm of the 'r'.

When you say book, I take it that this will be printed? About the colors, it is hard to judge without seeing the type of work that you'll be showing.

Keep us posted.

Using several colours against a grey background will produce some problems as some of the colours will approach the background tonally, just as yellow might against a white background (the more variety in colours the more chance of this happening). I think you have done quite well, though perhaps the grey is just a fraction too dark. Some colours project themselves more than others and this is also an important thing to remember.

For something similar in typography you might enjoy Theo Van Doesburg and Wim Crouwel.
For some more ideas about colours and how they project forward and or sit back, maybe Hans Hoffman.

I too prefer the first one, the second one is too Tetris!

I agree with 1985. The issue is that some of the colors you are using are approaching the same value as the dark gray...specifically the purple, so visually the purple sections are disappearing.

Multiple colors are OK but make sure there is a strong value contrast between the colors you are using in the type vs. the background color.

As others have said, the gray is way too dark.

I would prefer to see some pieces from your actual portfolio before we begin judging how the portfolio should be designed... that way we can get a general idea of the type of work you do.

i like the futuristic composition of colours :]

... and with the purple disappearing and the f descending (since when do f's have descenders?), I first read "Portpolio." Otherwise, with a bit of work, potentially cool stuff though.