In general, I judge strings mainly based on the following criteria:
I installed the GHS Gilmour strings on my Fender Stratocaster (w/o rolling nut). They needed quite a bit of stretching to settle, but no more than other strings, and they seem to behave well with the whammy bar.
1. Tone: Snappy and clear more than round and mellow. Still, the nice woody clean tone a strat can produce is there in spades, possibly related to the heavier bottom strings, and the sparkle on top is there too. All in all, I think these strings bring forward the inherent tone qualities of the strat, but they will not help you achieve the punch of a Les Paul-style guitar in a strat.
2. Playability: Heavier bottom strings invite you to hit your power chords a little harder, and they take a bit more effort to bend, but the balance between strings is still good. The strings don't feel particularly stiff nor soft, making vibrato and bending easy enough, but not as easy as with pure nickel strings.
3. Durability: Still a bit early to judge them concerning breakage, but sound-wise they seem to hold up very well. Some strings sound dull after only a short period of exposure to air and/or after a little playing, but I can't hear any difference in these after 2-3 weeks of regular playing.