Depending on the game, it's still the primary source of info for me. I have more games than time so I like to do as much as I can in as little playthroughs as I can (i.e. get true ending in first go) so it's typically the best source of information for me (again, mostly depends on the game - newer games seem to have better info on official/steam forums and/or wikis). I hate video walkthroughs because either I have to listen to a lot of useless crap for the info that may or may not even help or I have to figure out which specific video has it when there are tons of competing videos (i.e. Let's Plays). I.E. I like to watch Fightincowboy's videos of the Souls Series, but there's no way I can easily keep track of that info if I ever wanted to refer to it (Souls is one of those games I prefer watching rather than playing anyway).
Can't say I've noticed the forums being any worse than any others. I guess I do notice the signatures, but for the most part, I don't think those people are posting in the same forums for the games I play.