I've never owned one, but all the local rando-nuts told me not to get one because of this reason. Most of them have plastic bags cut and rigged up to protect theirs, and there are still failures.

I got the eTrex 20, which has a better reputation for weather protection.

Edit: Note of course that a rando ride in the PNW will sometimes involve 7-10 hours of riding in moderate to heavy rain. Those conditions may be outside the area of concern for most (sane) users.