If you're unfamiliar with classical music or think you hate it I have this advice: classical music is not particularly easy to make sense of, you need to play a given piece a number of times before your mind will make sense of it. The worst case of this I have ever encountered was with William Schuman's Third Symphony (William Schuman is a hardly-known modern American composer not to be confused with Robert Schumann, the well-known German composer). After playing it 10 times I could not make any sense of it and I put it away for almost a year before trying it again, but then suddenly it made lots of sense! Minds are funny that way, they work on material unconsciously to try and make sense of it. So please don't give up on classical music after playing a piece once or twice, do it day after day until you appreciate it (although of course it is possible that you picked a piece that actually IS meaningless junk, much modern music is meaningless junk).
It seems that its been pretty well established that music by Mozart will at least temporarily increase your intelligence but I suspect it does more than that, I suspect that the music actually transforms the way you think about the world. Much classical music is inspirational and really is a celebration of life, thus it instills hope and optimism. It shows us that there is a more beautiful world than this one.