I have a friend that rides a hayabusa (i think from 2003). In the first production years there are like every new model some little issues and things that didnt work as well. But from my point i think the hayabusa is over all a very reliable and strong bike.
I had a Gen1 and a Gen2 they both crash as well as each other.
The Gen2 has better suspension and brakes...the newer Gen2's now have Bremobo calipers but have retained the Nissin MC's...which makes the Brembo's moot IMO. These bikes are heavy and need good brakes...I believe they also now have ABS as standard too.
The Gen2 is a better machine but the Gen1 has a trimmer bodywork. They are very fast and very comfortable.....even on long rides, although the seat is a bit hard. Some early models had problems with the gearbox shafts bending....due to them being hollow. They fixed it on later ones....Gen2 doesnt have the same problem.
08 models and earlier had some problems with the clutch screws backing out and scouring the inside of the cover. And a slipper clutch was fitted to later models...Gen2 for sure have them...some bikes damaged the crank case clutch idler spindle by kicking back if the battery wasnt strong enough to spin the motor up...dont think any Au models had this problem.
One final thing is the reg/rec connector....under the belly pan....on some models this melts due to Suzuki's past habit of dumping excess voltage generated back through the alternater windings. The reg/rec is out in the air on the Gen2's...may also be on some later Gen1's
The fairings are a pain to get off and back on...there is a particular method....and often the crappy little clips will break.
I used to have the bike on a rear stand and using a small block of wood under the collector box and a floor jack to raise it level, (ONLY WITH THE ORIGINAL HEADERS, titanium ones are too thin and will buckle) carefully spread the belly pan to gain access to the oil filter to do an oil change without having to remove the fairings.
These are a fantastic machine with way too much power for some, even me apparantly, and pulling power that is totally unbelievable.