Some of the kits I've had from Brewer's Best have been really good, some just ok. Age of the kit might really be a factor.
The other thing to keep in mind is that those BB kits are designed to be a middle-of-the-road representation of their styles. Some styles are sort of bland, to be honest. I mean, a cream ale isn't going to have much flavor. If you made an IPA, though, or a stout, I'd expect some flavor!
I'd suggest trying a freshly made kit from nothernbrewer.com, or austinhomebrew.com. AHS especially- they have literally hundreds of great extract/steeping grain kits. I've made many of them myself over the years, and would recommend them to anybody.