I love to hate them...They aren't perfect, sure and can at times remind me of the cliffracers from morrowind. But they add a good mix-up to combat and are a bit more immersive than those bees were. The bike chasing does tend to get a bit annoying - maybe the give-up time should be set a lot shorter. I don't want them to go away though.
This topic reminds me of something I thought of tonight while playing - I think it would be beneficial to have a quick look-behind button on the keyboard for when driving. I know you can switch back and forth between mouse and keyboard steering and look back behind you that way - but it's too slow and clunky - I think being able to map a button to just quickly look behind you while on a vehicle would be useful for all kinds of things - including vultures.