I wonder if part of the reason why people are so unimpressed by the soundtrack is because we haven't listened to it enough yet for the music to grow on us like the music from the OT did. After all, we've had decades to listen to the OT soundtrack in repeat viewings of the movies, the soundtracks by themselves, and in countless video games so by now we're intimately familiar with the music. But try to think back to when you first saw Star Wars, did the music stand out to you then? I'd bet that it didn't, outside of the opening theme that is, and it wasn't until years later that you grew to recognize all of the themes and really appreciate the music but time has blurred that recognition so it only seems like you fell in love with the music right off the bat. Personally, having seen Star Wars when it first hit the theaters in '77 at age 7 or 8, I can't say that I remembered much about the music back then, it's only later that I grew to appreciate it. I'm thinking that over time, as we all watch TFA over and over again, and listen to the soundtrack over and over again that we'll grow to love it and pick out memorable themes like there were in the OT.
@nienumb1 If you looked at the credits, John Williams wasn't the sole conductor for the soundtrack, he was credited along with someone else as co-conductors and Gustav Dudamel was also listed as a guest conductor. So it's entirely possible that he didn't conduct the opening theme, or they might have used an existing recording and used a bad mix.