I love these strings, they are the only kind I've used for a long time in my electric guitars.
They are thin, easy to play and easy on the fingers but still retain good volume and brightness. (I have tendinitis in my left wrist and I find these help me make keep the problem in check, however I would still use them If my wrist was fine).
The only cons I can see is the fact that if you drop the low E string to D it will loose a bit of volume and the string will vibrate a bit harder of course, as the tension is not perfect for that tuning, I do enjoy this effect, but others might not, so keep that in mind.