Re. whether the Brotherhood are good, I think for non-gamers it might help to explain a little about how Fallout (and games like it) work.
In Fallout games, it isn’t a case of completing level 1, moving onto level 2, level 3, and doing what the game tells you to do.
Instead, you’re in an “open world”, meaning that you’re free to explore the setting of the game in (largely) whatever order you want.
Each game will have an overall, core story and lots of optional side-stories. You could complete the core story by taking the particular steps needed to progress it, without actually exploring most of the “world” of the game.
Both the core story and various of the side stories will not have a single, fixed narrative but instead will work more like a choose-your-own-adventure book, where you make decisions and they will lead to a wide variety of outcomes. The core story won’t have just one ending, but a range of possible ones, based on your decisions. The actual world of the game will evolve based on your decisions too (most obviously, if you choose to blow up a certain town, you won’t be able to visit it anymore or complete the side-stories that might have been available if you hadn’t killed everyone relevant to it).
In the Fallout universe in particular many of the decisions you will have to make will be more nuanced than “be a goodie/baddie”, and may be far more morally complex. Admittedly, there’ll be some obviously good/evil choices too.
In Fallout 4 there are four different groups who you can align yourself with (including the Brotherhood), each with their own aims, philosophies and motivations. Some are plainly more dubious than others but they all perceive themselves to be serving the greater good.
It’s probably fair to say that the Brotherhood aren’t “evil”, and in some conflicts they might be the obvious “good guys”. In the story of Fallout 3, they are the obvious (flawed) goodies. In Fallout 4 I’d say that two of the other three factions have a much better claim to be “the good guys”, though opinions may vary!