I enjoy it, and the rp capabilities. Im just worried about replay value as well as the ability to squander 60 hours just running around doing the little things.
Well there are four main paths to the main quest once you get to the Strip, there is some overlap in what they ask you to do (or at least your options) but they're distinct in their own ways.
With my second character this is one group of quests that I'm repeating but so far I've mostly kept to new quests. There are also two settlements I haven't even been too yet as well as several major locations I haven't seen. The world may not be as large as the one in FO3 but there's still plenty to do and at least for me lots of replay value.
It is slow to start if you're following the main quest but the world will open up

I wouldn't worry. Not unless you plan on skippin' through the quests. I've got 83 hours with 68 quests completed and 116 locations discovered. And I'd reckon I still have another 10-20 hours left before I've finished the thing. And no, I'm not dawdlin'. I ain't racin', but I sure ain't dawdlin'.
I was trying to finish up the main quest fairly quickly and it still took me 50 hours.