I currently have Star Specs (235/40ZR -18 front and 265/35ZR -18) and so does Skelekitty. We both like the tires--they're great all around, decent in the rain, great for back roads, and seem to do quite well at the track. I prefer them to anything else I've had so far.
I can compare them with the stock Contis, PS2s on an E92 M3 and Cayman S, and Sumitomo HTR IIIs on the Z4M.
The stock Contis were total crap, and I won't comment further on those.
Compared to PS2s, the Star Specs have more grip and less lateral slip, and are a bit louder. I prefer them to the PS2s for spirited back road driving as they seem more precise. The Star Specs are a bit less comfortable and have more road noise than the PS2, and they're less expensive (although Star Spec prices keep going up, so how long that will be true no one knows). The PS2s are a bit better in the rain.
The Sumitomo HTR IIIs are a really good tire in the wet. I put well over 100 miles on them on my way home in a really bad storm (very heavy rain) and no hydroplanning or other "excitement" to report. On dry roads they're pretty good, but no where near the PS2 or Star Specs. Comfortable though, and reasonably priced. If you're not going to do extensive canyon carving or track work (or Autox) they're a pretty good tire (no word on wear, I had them on for under 1,500 miles). They are not suited to the track at all. The small tread pattern is tailor made for squirm and even with pitting to check pressures (tried 38 and also 39 hot all around) they get very greasy, have poor (relative) lateral grip, and get hot enough on surface to allow a finger to deform the tire. I had no such issues with the Star Specs.
My wife had even wear on the Star Specs (prior to taking the car to the track) with a mix of highway, city, and back roads driving with -1.5 front 1/16 total toe and -1.8 rear 1/16 total toe. Current setting (as of last week) is -2.0 front zero toe and -2.0 rear 1/16 total toe.
I've run 39/37 hot with the Star Specs on the track and moved that down to 37/37 the last couple of sessions (no rollover, a bit more bite). I really need a pyrometer...and I'm still playing with what might be an "optimal" pressure. I know several folks running 39 all around hot with this tire, so this is by no means a recommendation just a "here's where I am now" kind of thing.
My settings are -2.7 front zero toe and -1.9 rear 1/16 total toe. Too early to really comment on wear, although the car sees weekend/track duty it's not a DD.