I hunt there a good bit, some general comments, from my experience:
Hunting pressure during archery can be high, but it varies from week to week, year to year, and area to area, you just never know how many people are going to be camped in spot X during week Y.
Since CO has gone to unit specific muzzleloader tags the pressure from those guys seems considerably less than it used to be, so don't rule out hunting that week, at least for that reason, you will probably see more archery hunters.
As with most OTC areas the bulls are mostly raghorns, with a few decent 5X5's. Very rarely do I see a good 6pt bull.
It is big country and the elk will get pushed around, if you are not seeing elk, or very fresh sign, go look somewhere else. Cattle drives have on occasion negatively impacted some areas I hunt, and they move the cattle alot during this time of year.
Regarding weather, early season can be late summer pattern, cool mornings (30's, 40's) with warm afternoons. If the monsoon is cranking you can get thunderstorms every afternoon which can cool it off considerably, always have raingear. If you kill something early in season be prepared for the warm temps and flies.
Late season snow and a few days of nasty weather are possible, although haven't seen much in last few years. Late September morning temps can be teens and 20's.
The season is unusually late this year, probably good if you like to hunt the "peak" rut.
Good luck,
JR