If you played either Fallout 3 or New Vegas, you'll have an idea about what to expect. Yes, it's more of the same overall, with a few noticeable changes.
Settlement building is the newest addition. It's a great idea, though a bit poorly implemented, requiring Perks to really taken advantage of the concept. It can be fun, however, and I definitely spent way too much time doing it. The world is massive, and it's easy to ignore the mostly forgettable main story to forge your own path in the world, which is wide open to your character, so long as they can survive.
There are some poor design choices really holding the game back. Repeating radiant quests involving certain characters are more annoying than encouraging, unless the idea is to make you the player want to quit the game. Now your character is voiced, but that aspect doesn't add anything and instead detracts from how conversations are structured, and there's a to of sameness to many of the environments/locations, meaning you go in, clear it of whichever enemy type is in there, pick some locks, hack some computers, rinse, repeat. More variety in mission structure would've done a lot to alleviate the issue, but it seems like the focus is on quantity over variety. You can easily play this game with one character for over 100 hours, but I'm not so sure that's always a pro given the repetitive nature of the core gameplay mechanics.
I did encounter glitches. Twice the game quit with an error message, but I didn't lose much because I saved often (seriously, save often). I also had some audio loop bug that just kept repeating, which was solved by quitting the game to the main menu. Funny how stuff like that works sometimes. There are some other minor problems. The framerate can seriously stutter at later points in the game when Vertibirds are around, or just when a large number of enemies are encountered. Or just because. Some of these problems will probably be ironed out at some point.
Overall, it's a great game that is perhaps a bit too ambitious for its own good.