I like a lot of things about Fallout 4, so much that it's making me excited about the things they could be adding with DLC. I'll reveal my top 5 likes about Fallout 4 below.
1. Settlement building is so much fun, I spend hours just putting the foundation together. Some reviewers on YouTube back when the game first came out compared this feature to Minecraft. I never played Minecraft nor plan too, as I watched a friend played and it's just too weird for me, making this feature kind of special for me.
2. Weapons and armor (non-powered) modding is simply amazing, I haven't seen a gear modifying system this intense since Army Of Two (original game of the series) and Army Of Two The 40th Day (second game in the series). I absolutely LOVE this feature!
3. Power armor modding just like generic gear modding is pretty intensely AWESOME! I love the part where you can paint it and customize it with newer parts, kind of like upgrading a PC or a vehicle.
4. The combat reminds me of playing Wolfenstein The New Order which I really loved, sometimes I forget I'm playing an open world RPG (in a good way) and getting worried it's gonna start the credit's in any minute (since FPS based games are pretty short in comparison to Fallout). I feel that since Bethesda included really awesome combat mechanics makes Fallout 4 largly superior to Fallout New Vegas & Fallout 3 (combat wise) put together.
5. The revamped perk system, revamped effects of the 7 SPECIAL attributes, no level cap, and the removal of skills from the previous games make the overall level progression very entertaining and makes it exciting when you level up and get to choose your perk.
Finally my favorite! I have to say I find nothing more entertaining that using colonial era stationary artillary on groups of enemies (when near a settlement) and the laser musket in most combat situations. This idea Bethesda came up with is absolutly one of the coolest things I have seen from them thus far.