After I took the Magento Certified Solution Specialist and Magento Certified Frontend Developer exams end of last year and in the beginning of this year, I finally also took the Magento Certified Developer exam. Conclusion: It is, as expected, the hardest of the three exams, but it is absolutely doable if you worked with Magento for more than a year on a full-time basis.
As I expected the exam to be the hardest, I planned to prepare for it. I collected links and resources in order to have a look at them at some time, but actually I did not have the time for it. Anyway, the list may help you to prepare, so here it is (in no particular order):
- the official certification study guide
- the Grokking Magento book (hey, I actually read this one – nice one!)
- Study Group Moderator’s Kit
The exam is, as the time of writing, based on Magento 1.8, includes 72 questions and you have 90 minutes. Again, 90 minutes were more than enough. Two of the questions are unvalued test questions which may be included in future exams. What surprised me the most was the rather low passing score of 37. I think the passing score was higher for the other two exams.
In the end, I passed with a quite good result. Funnily enough, the score was really high in categories where I expected some problems (like EAV or API) and it was a bit worse in categories where I bet there should not be any problems (like catalog or checkout).
So if you develop Magento stuff on a daily basis for approximately more than a year, you should be good to take the exam. Good luck!