On one of the laptops I have Haiku on, using the trackpad mouse can be a bit frustrating. Acceleration is set to the fastest value but the mouse still moves slower than what is possible using Windows on this same computer. Maybe Haiku is able to implement a way through software to accelerate even further, I think there was a Linux that did such a thing as well. It would be useful for naturally slower mice like these.
Another issue at least on this laptop is the trackpad touch ‘tap’ (which equals a left click). The tapping is slightly delayed compared to the normal tactile left click button. So for example left clicking a button, it highlights the button immediately as expected, but using tap-to-click it registers some milliseconds later. But that short amount is enough to make double tapping (for example to open a desktop icon) near impossible. This is a software/driver issue in Haiku because tapping works perfect with same reaction speed as the tactile clicks when using Windows on this PC.
On a related note: I have a trackball USB mouse called Kensington Orbit which unfortunately is not compatible with Haiku when I tried. I hope a suitable driver for that would be found.