I was really disappointed in Fallout 4 and how it plays. Perhaps I've just become so spoiled with a fully-modded Skyrim,
so I'll just wait till there are plenty of mods for Fallout. Anyone else felt disappointed in the game?
Don't forget that Skyrim has a ton of DLC content, not just a lot of mods.
The main reason I feel a degree of disappointment is that you have to start over 4 times to experience each faction. There is a lot of content in there, but getting at the remaining content involves diminishing returns. In Skyrim, except for the civil war factions, you could play all the factions with a single character, if you so chose.
There are, however, several strengths, many of which get taken for granted by the gaming community.
1) The power armor is "real". It isn't just an item you click on in your inventory. It's a framework which holds pieces, and you get to craft each piece to the best of your ability. The main dislike I have w/r to the power armor is that there are very few "legendary" power armor pieces. (Well, it's not as if power armor NEEDS them

... ) As such, if I have a full set of "normal" armor legendary pieces that I like, the power armor feels a bit weaker.
2) Crafting weapons and armor is awesome. It's better balanced than in Skyrim, and you can't take advantage of logical loopholes to make super powerful items. Also, there are numerous options to add, and the available options depend on the particular framework you're using. My only criticisms of the system are nitpicks: you can't build the base frameworks (e.g., a base pipe pistol or base laser gun), and the melee/unarmed weapons mods are extremely limited.
3) Building a town/community is very rewarding, both in terms of gameplay and in terms of material rewards in game. They really should have put out some "official" tutorials on how to build things, though, for those who don't find the controls intuitive. There are a lot of "secret" ways to build things that you just wouldn't be able to figure out on your own without experimenting with every. single. component. Once you get a lot of farms going, you have so much food/water production that you can just sell it to merchants (and you can add more stores/merchants to sell to!) and make plenty of caps from that. Finally, watching your town get attacked by raiders or super mutants and repelling the attack all on its own (with the help of the dozens of turrets that open fire on them from hundreds of yards away!) is quite spectacular. In the particular case I'm thinking of, it was at night, and I had specifically clustered my turrets in a particular way (high off the ground, covering common approaches), and I didn't have to raise a finger. Every time a raider poked his head up over a hill, the turrets would spot him and all fire simultaneously. They simply didn't have a chance, and at night it was quite an awesome fireworks show.
4) The companions are all interesting. Of course you'll have your druthers as to which personalities fit best with your own, and some stories/quests are more "spectacular" than others. It's totally worth the chore of finding them, meeting them, and working with them on their quests. (I am very tempted to say more, but I don't want to spoil anything.)
5) If you don't like having a companion, there is a great set of perks available at 3 Charisma that benefit you only if you have no companion (Dogmeat doesn't count as a companion w/r to these perks). With all three, the damage you take is reduced by 30%, you do 25% more damage (period, to everything), and you can carry 100 more lbs of weight. I've been using this on my 2nd playthrough in combination with the "Rooted" (+50 % melee damage, +50 DR) and "Strong Back" (+50 carry weight, run when encumbered, fast travel when encumbered) perks, and it's kind of awesome. You really feel the difference when you join up with a companion, as enemies start hurting you a lot more.
6) There are some very fun and interesting side quests in the game that are way more than just errands and are entirely independent from the main plot line(s). (Highlight to read the following minor spoiler:
for instance, the Silver Shroud quest line, or meeting up with the Atom Cats.) If anything, the game needs more of these, which I expect will happen with future DLC.
Anyway, I expect I'll be replaying this a few more times as the DLC comes out. My main hope is that the DLC will be more like it was in New Vegas than in Fallout 3.