I've gone through several sets of HTC ZII and ZIII, on my e30 and e36 BMWs. The best words I would use to describe them is "acceptable", and "cheap as hell". not great or even above average for most things (dry grip, wet grip, noise/comfort) but damn, $70 each, right!
The "cheap as hell" makes up for a lot of performance shortcomings in some cases. The tirerack user surveys rank them mid-pack in their "max performance summer" category, and I usually find the aggregate user surveys to be pretty accurate. But I think that in this particular instance the tires are maybe over rated a bit because people are biased and impressed by their extreme price point/value and inflating the performance numbers, consciously or subconsciously.
When I was driving all over the place to auto-x every weekend, and running some super aggressive alignments, these were my go-to tires when a set of tires only lasted me 10k or *maybe* 15k miles. On a dollar-per-performace scale, these rank super high.
But if you're looking for a summer tire and can afford to spend $450 instead of $280, I'd strongly push you towards the Continental extreme contact DW (not DWS). I liked them well enough to put them on two of my other cars recently. An advantage to the Conti's that not many people know is that Conti's automatically come with road hazard coverage from the manufacturer, like the kind that you pay $17 a tire for at Discount, tirerack, or wherever in case you hit a pothole or get an unrepairable nail or something. Definitely should factor in if you are the type that buys road hazard certificates on tire purchases. Even without the road hazard thing, I would recommend them (I'm not a road hazard guy). I like the Michelin pilot super sports on my mz5 even more, but they are another chunk of change.
tl;dr - HTR ZIII are a great value, but only an adequate tire. If you can find another $150 in the tire budget, you can get a better tire.
