Considering that the lumia 925 can be had for around $200 new and has better camera, more ram, higher resolution, and wireless charging capability, I'm not seeing much of a reason to get the $189 lumia 635.
The biggest drawback of 925 is the non-expandable 16GB memory. C'mon, when you have a phone that can take hi-res photos and videos why only 16GB memory( you can use one drive but what about music, videos and other content you want to access offline?)? I read in reviews that even the battery life is bad. These are two main factors why 925 is a flop among power users. If you want a device with better battery life, expandable storage, decent camera, newer OS and on-screen buttons - 635 hits every point. Also, I think dual-color rounded plastic shells looks much cooler than the boxy aluminium industrial design.
Being "metalchick" you should understand how it feels to have your music collection in your pocket all the time! Battery life depends on the user. If you are able to juice out 36 hours, that's great! Even I'm a music head n I want all kinds of genres and bands on my phone. I'm not a photo geek so a camera to snap some casual photos should do good on 635. Yes, the lumia 925 is better no doubt but I think limited space kills the premium experience... I'm definitely getting the 635 next month!