Personally I dont think its that quick of a level up I am only at level 6 or 7 after 14 hours of playing and I just now got onto the strip.
Aside from that it is more dangerous. You can run into pockets of thugs as well as pockets of radscorpions.
Spoiler There was one part in the very begining when I desided to head south from Good Springs and I ran into not 1, not 2, not 3, but 4 radscorpions at the same time. Then I also ran into three fire geccos which ended up killing me 5 different times and I am playing this on normal.
Not to mention the fact that weapons are pretty hard to come by and your currency is always near broke while playing the game.
I am still learning as I go but so far I have to say theres alot of twists in the story and alot of different options you can take. Having real fun so far and the map is pretty big. I think bigger than FO3 cause its taken me for ever to go from the center of the map east towards the Colorado river.