I recently took the Acquia Developer Certification exam on a whim, and it was quite a memorable experience. I signed up for the exam around noon time, to be taken at 3:30PM. I took the test online, which was interesting. The software they use assigns you a "proctor" who basically monitors you. You can't talk, or move out of camera view, and can't wear a necklace or a watch (yes, they will have you remove those items).
I read up on the exam and what others had posted about it. I was a little concerned when I read that webchick, a Drupal core contributor, had gotten 85% on it. I for one am not a core contributor.
But I do live and breathe Drupal.
How to Prep
Aside from the fact that you really can't prep, there are some pretty standard things you need to be familiar with. The Acquia Certified Developer Blueprint is about a good a place as any to start.
The format for most questions was multiple choice, and the occasional "pick 2" or "pick 3". I found the questions to be mostly unforgiving (no easy guesses). This is the kind of test you cannot really study for (so I didn't). Most of the questions are scenarios that describe a problem, e.g. a bug, feature request, caching issue, client error, etc, and then you pick the best solution to solve the problem. This means that the test covers a huge breadth of knowledge: understanding Drupal core APIs, HTML, CSS, theming, customizations, Views, caching, and more.
I can't really give much advice on studying for the exam aside from this: Build things the right way.
A lot of the test questions is knowledge you would gain from building several Drupal sites with some customizations. Assuming you are building them the right way. Many Drupal developers choose to work "the easy way" and take ridiculous shortcuts; if that's you, the test is going to be near impossible.
I got a 90%, which was actually higher than I was expecting, given the number of answers I gave I was unsure of.
- Fundamental Web Development Concepts: 100%
- Site Building: 81%
- Front end development (Theming) : 100%
- Back end development (Coding) : 86%
What Does it All Mean?
As a partner in a web development agency, I have to consider the question, "What is the point of the exam? Does it have merit?" After taking the exam personally I have derived two facts:
- The test is hard. Only someone with great Drupal knowledge and experience could probably pass the test.
- The test is tricky. I can definitely see where someone who couldn't pass the test would still be a good Drupal developer.
So I believe that, in general, if you can pass the test, you must be a good developer, but if you fail the test by a small margin, it could just be you're bad at taking this type of test.