Some users of BrainsBreaker that played with version 4 told us that they miss the more sharp pieces from BB4.
I was thinking that maybe you haven't noticed that there's an option to "force" the contour of the pieces to be more sharp.
Try this: Load any puzzle, go to the options (pressing the key F3 in Windows or in Mac fn+F3). Look the options near the bottom "Piece borders:", click on "Sharp" and see how you feel about it.
The effect in sharp mode is more noticeable with small pieces
Now that you are at it, you can try the others to see the difference. Bold may be useful with a small number of pieces, when they are quite large. Kids like this especially. But for more advanced puzzlers thin or sharp will allow to see more clearly the subtle variations in the jigsaw cut of pieces.
We hope you are having a great Summertime (or Winter), we are here working hard on new offerings -initially for Android- that should see the light soon.... (And quite excited with the results, eager to know what you think of them)All The Best!