I think you have a great design, but having the letterpress effect on every post/project title and button on the site is a bit overkill. There is one usability issue that I noticed. On your contact form, you have the value set for the inputs, but they don't disappear when the user clicks inside the input. I would recommend checking out this: http://fuelyourcoding.com/in-field-labels/ or something similar.
You might have a fantastic portfolio, but if I were looking for someone to design a site for me i'd be instantly turned off by this and I doubt i'd even click on your portfolio link.
Your actual layout is fine, but all I see is a lot of white and grey and some blue. It's boring and as a designer showing off your services you should show how creative you can be. I realise that your objective was usability but that doesn't mean your design has to suffer!
Definitely try incorporating the cartoon style you've got going on at the bottom of the site a lot more. =
The strongest in your design is your cartoon logo. I think you should play more with it (if that´s who you are). The rest of the page does not match up with this logo. For once I would remove the photo to keep the cartoon style, and play with colours, fonts - more rock n´roll!
Apparently you want the users to press the button TIenes algun proyecto... , then why don´t you make this button clearer and more exciting?
I like it but it seems as though the whole site is on the home page.
Also the sub headings come after the content, think it would look better if they were above
I like it, however I think you may want to add in another color for the things you really want to stand out. The headers bars with the gray text also need a little more variation as they blend. I like the clean look to it.