The major plus point is just how flexible this bike is. It's as happy at going for a Sunday morning blast as touring across Europe. My mates ride a Honda RVF400, Ducati 916 and GSXR600-K4 and the ZX6-R can still hold it's own in that company on any weekend ride out. My old Ducati used to make my shoulders ache after 200 miles or so but the ZX6R gives me no such problems, unlike my mates bikes. I took the ZX6R to Germany in Summer '06, doing about 4-500 miles per day (try that on a 916), complete with soft panniers, tank bag and a small rucksack. The bike stayed very composed and the luggage didn't upset the bikes handling anywhere near as much as I expected it to. With luggage, it will still happily cruise all day at 100mph but will easily run up to 120mph as and when you need to with handling that was stable and good enough to be fun, if not exciting. As you would expect when touring, I rode it in the rain and it stood outside overnight but I've had no problems with corroded fasteners, though judging by the muck under the hugger, they're well worth having. Without the luggage, I took it around the Nurburgring on my way back home. It was very forgiving compared to the slow steering Ducati and saved me from at least one accident.
Sounds fantastic when you cane it, even without a race can and still plenty of bottom end too. Loads of comments about the ZX6R being not as good on the road as the CBR600F and not as good on the track as the R6 which is a very pessimistic way of looking at it. Personally, I see it as a better road bike than the R6 or GSXR but more of a hooligan than the CBR-F, ZZR600 or Thundercat. Overall, it's definitely a jack of all trades but that suits me fine.
Bad points are; carb icing on cold mornings; brakes lack feel (braided hoses coming soon) even though they do work well; cost of the major service (valve clearances); no fuel gauge and the fuel tap is impossible to operate on the move (I use the trip meter and get about 120 miles before reserve); The clocks require a definite look down and need more than a glance to take in any info (This and the fuel tap/no gauge are my reasons for giving only 2 stars for equipment). It does lack the pose factor of the R6, GSXR, CBR-RR but you can't buy a nice one of those of the same age for what I paid for my ZX6R with less than 10k on the clock.