I find that in the last few years percussion writing in new music is getting stronger and better all the time. I like more rather than less detail, but not so much that it completely clutters the page. I like a clear indication of mallets, i.e. marimba, vibe, glock, snare, etc. And I appreciate knowing mallets should be hard, soft, or medium. I find it very helpful to see a schematic drawing of a percussion setup. It indicates to me that the composer knows what he or she is doing or has gotten some help in facilitating future performances. It also indicates that the composer has thought about the difficulties inherent in multi-set-up pieces. Another thing I like is when a composer indicates some flexibility in choices. For instance, an indication to use double ended sticks often means the composer is aware of the difficulty in carrying too many sticks at once and realizes some freedom is necessary to help the performer arrive at satisfactory performance levels.
I find that often mallet damping and pedaling is included but that phrase marks and articulation are infrequently considered. I find the latter very helpful in creating a more immediate musical result and wish that more composers would keep that in mind.