I have had and used the Shure SRH1540 for over two years now and they have steadily become little more than a decoration / headphones I sometimes use for sound design.
Short version:
If you want to enjoy music (regardless of the genre) I guarantee you there are better and more dynamic sounding headphones than the SRH1540, which are still accurate for the same price or cheaper. The SRH1450 does what they are designed to do - very neutral sound, nothing exciting, very 'true', so for music it sounds 'nice'. I own a small army of high-end over ear headphones and these have very quickly become the last ones I would consider to simply listen to music.
If you are looking for very accurate neutral headphones for video or sound editing - these are great, although pricey for what they deliver considering the alternatives.
Finally;
For anyone arguing that they just need a 'burn in' time - the sound signature on mine has not changed much after hundreds of hours of use and in my opinion if you are hoping they will 'improve', they wont.
If you buy these and try them the first time with your favourite amp or DAC and they don't make you smile from ear to ear, send them back as they will most likely not grow on you.
The build quality is excellent, they are super comfortable for a bigger head and the included cables and extra ear pads etc are great, although the case is very impractical for anything other than storage (its HUGE).