Not much different from a 737-800.
The two rows in front will more likely be 3x3 covered in black/grey leather, and no purple divider.
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Would there not be big difference in the leg room? I've never sat in row 3 in either aircraft, but there does seem to be a lot of room in row 3 in the 737-800 with K class. In the 737-700, it looks to me like the leg room would be the same as any other standard row on the plane.
(I'm guessing you are already on the plane now, so you will know better than me at this stage..)