Way back when, in the 1970's when I first started to play guitar, Rotosound were THE string to use. All the pros used them, so they were like an aspiration purchase. (I remember Mike Rutherford of Genesis used Rotosound strings on all his guitars and advertised as such)
The strings are still great and have a lovely ring to them and sustain. I use them on my Strat and they suit the guitar fine. I've NEVER had a breakage using them live or in rehearsal and so find them very reliable, and that matters if you play out a lot!
So, therefore not only do they sound great, I have great confidence in their durability and longevity. The free top string is a bonus if you are a hard hitter and snap them, but I've never had one snap!
All in all they are great and I would recommend anyone to get a set and use them, I can promise you will be surprised by the quality and question why you hadn't used them before.