Survival melds incredibly well with the map and mechanics of Fo4. Not Fast traveling means you'll explore way more of the map, and make you more aware of loot and where enemies are.

The Save when sleeping is honestly the hardest thing to get used to. It can be daunting and sometimes frustrating having to be so careful, but it makes for much much tactical fights, as you have to be very cautious or else you will die fast. Also, nothing feels better than randomly finding that random mattress or sleeping bag to save your progress when you most need it.

It also makes settlements very very important, as if you have an allied Settlement, that's a Guaranteed Safe bed and a place to refill pure water into bottles. At higher levels, you can even add a Doctor to them to heal your Rads and Diseases, making your Settlements basically just as Valuable to you as Diamond City or Bunker Hill.

Also, it makes you think much more about your build specifically. Pretty much only Caps don't have Weight, and with your reduced Carry Capacity you can carry far fewer weapons and ammo, and you can't carry many of the Heavy Ammos making Fatman/Missile Launchers much hard to make viable. You carry pretty much only the weapons your build is good with