Attraction/lust is important from the start, however I think people having the same life goals and beliefs really plays the biggest part in how a first date goes. Think of it like a job interview, you are both there to see if you have something to offer each other and want the same things. Each party in a job interview has to be attracted to the other, the employee is attracted to the pay and the employer to the skills.
In the end, no matter how much you are attracted to each other it won't last long if you don't want the same things in life. The best and most honest people won't continue past the first date if they don't see a future.
Thanks for the response! I do agree with you. Perhaps the most important job interview of your life as well, no pressure there. Heh. There are definitely some deal breakers out there, you can usually tell if someone is entirely unsuitable. It does annoy me, however, when someone gets 'dumped' (in lack of a better word) when there isn't that immediate click but everything else matches up...or for that matter, something small that the other person did that could just be down to first date nerves. It has the potential to get there when you know someone better, and younger people (than me anyway) now seem to only look for that instant gratification!