I took BEC in February. I used Becker and got a 52 on mock exam 1 and a 64 on mock exam 2. I passed the actual exam with an 89.
I thought the actual exam was easier than the review material. For me, the Becker MCQ's were harder than the actual exam and the Becker SIMS were about on par with the actual test. The writing section is pretty much free points. I printed out Becker's responses to the writing prompts just as a guide for how to frame my answer. My actual responses to the writing prompts were much less detailed than Becker's examples.
For the MCQ's – I would say know the COSO framework, ERM, and IT sections very well. A lot of people will say Becker is lacking in their coverage of the IT subject matter, but I thought they did an adequate job covering such a broad subject. I did get 2-3 IT MCQ's that I had never seen in the Becker material, but I was able to narrow down the choices to a 50/50 guess using what I did know.
For the SIMS – I would say know the cost accounting variance material very well. PURE DADS was a savior here. Half of my SIMS centered around direct cost accounting variance material.
There is a spreadsheet floating around on the internet somewhere where a guy keeps track of everyone's Becker mock exam scores vs. actual exam scores and BEC by far has the biggest “bump” up in score among the 4 exams. The average “bump” up in score between the BEC mock exams and actual exam is something like 24 points. My scores went up 25 points, so I can personally attest to this being true.