I'll admit that I haven't watched BW at any point, or most of AG or DP, but I will comment from these statements that from the little I've heard of them they are really doing badly in terms of storyline. The only improvements I could think of for BW is that they stopped the skirt chasing gag and they made Team Rocket somewhat more of a threat than before, and maybe Iris not being a FAS, that's it. Even then, that's pretty much because Brock was removed when they could have just tried to, you know, actually alter his personality to not be a Charlie Harper kind of person, or heck, actually have Team Rocket at least try to beat a pokemon that is a rookie, as that would have been more than enough to prove they are more dangerous than before (since their first actual loss, barring Episode 2, was against a Caterpie that was not only completely inexperienced but also at critical health, that would have been a perfect way to show they aren't fooling around anymore), and its still undecided as to whether she is definitively not a FAS (She'd need to be in a situation with FAS's where she doesn't react like them, similar to how Misty didn't react with the FAS's in Princess vs. Princess).
Ash was completely butchered in this series, essentially. He's currently losing at battles that he should be able to beat at a whim, not to mention that at least in the first episode from what I heard, he's actually making rookie mistakes. "Pokemon Master", by this rate, he's becoming the worst trainer ever. At least in DP, he actually seemed like he knew what he was doing. And as evidenced by what Pikachu had to lose against (which isn't entirely BW's fault, as it happened in DP and AG as well, but it is still at least partially BW's fault), this is getting way out of hand. Honestly, the writers/animators either need to get their act together and actually demonstrate that Ash is a veteran, even if it meant giving him something of a Solid Snake-esque personality, or they have to replace him with someone new. And for the record, its also not benefitting the target age group (little kids) either, as AG's ratings sank below the original series, and DP's ratings similarly sunk below even AG's, and I predict that BW's ratings will inevitably sink even further. The only other possibility to the ratings sinking among even the target audience is if Japan is experiencing a birth decline, and its obvious that they aren't.