The pages themselves are relatively simple, the homepage should follow the current best practice for Saas type products with clear presentation of the proposition, benefits of the product, and a well executed brand throughout.
The form is very important and needs to include in line validation as the user goes through the form, like the twitter example in this article http://designmodo.com/ux-form-validation/
The product name and logo is attached and the font is Sansus Webissimo
On the one hand, Some gentle element of 3d, common in the examples that I have given here would be expected and very much of the current fashion. This is useful in highlighting the structure of the pages and helping the user navigate.
On the other hand, I think that the microsoft-inspired push towards flat design http://fltdsgn.com has a lot going for it - especially as it will be easier to read on smaller handheld devices.
I would like to see concepts taking both approaches.
In addition to the brand and visual presentation on the homepage being important (as you would expect) the form element - and in particular the visual presentation of the form is also extremely important for the following reason: People hate forms associated with HR departments, they are typically terrible, badly laid out, ask for information that the HR department already has and are unclear as to what has to be done next. Our form (even though it's only an incredibly simple one!) needs to be the opposite of this. Clear, obviously intelligent, a delight to use and straightforward - we want users to say "why can't all forms be like this!"