My Exam Pack 1 experience has been rather odd. For the free exams (1 and 2), I got 710 on each (48Q 40V and 44Q 42V respectively).
On Exam Pack 1 I got 730 (47Q 42V) and I just took Exam 4 and got 690 (43Q 41V).
Now for exam 4 I will say that there were many more distractions in the library today. I have woman behind me who insists on using her computer with volume turned up, makes loud phone calls with customer service, and is still making a weird grunting sound, and a guy who feels the best way to communicate is yelling at the person 2 feet from him. I also got fewer total answers wrong during Exam 4. Weirdly, I also had two of the almost exact same CR question back to back in Exam 4 (37 and 38) with the only differences being one answer choice and a slight wording change (but no meaning change) to the passage. I saw an unusual number of Inference questions.
After Exam 3 I saw my SC was the only thing I missed on VR. 4 days later on Exam 4 it's my CR (flawless on Exam 3) that's weak. On QR I saw more Standard Deviation questions than in any of the previous tests (at least 4). Two of these were very similar DS questions with different subjects but the same 1) and 2) data. Overall, the distribution of questions on Exam 4 felt very different and, I don't know how to describe the feeling exactly but, unbalanced. Also something weird has happened in the library for the even numbered exams.
I'm taking my test on Friday January 30th. I'm reviewing my responses later today to see what mistakes I made and doing some last minute review, but this last test seems weird. Let us know how your actual test came out

Prep Info:
Manhattan GMAT Books (Got laid off and moved in with the parents, no money for a class)
GMAT Clarity as a Lesson Plan
Diagnostic (GMATPrep 1) - 700 (scores on another computer)
GMATPrep 1 710 (48Q 40V IR7)
GMATPrep 2 710 (44Q 42V IR8)
GMATPrep 3 730 (47Q 42V IR8)
GMATPrep 4 690 (43Q 41V IR8)