45 minuten - 1 uur
I was stranded on a road in the middle of nowhere around midnight during a real bad rainstorm, and the other two flashlights I had were dead so, I needed to pull my iPhone out for the LED flash(light). Was able to fix my car enough to get it running, but my iPhone did get a little wet, enough to activate the dock moisture sensor, as much as I tried to keep it dry. All the parts near the bottom started acting up for a while, and eventually the mic stopped working, which is kind of a problem for a phone.
Anyway, it took about an hour from start to finish. I work on Apple's computer a lot so I was familiar with their internal designs. There was very slight corrosion on the speaker contacts, so I cleaned those which stopped my speaker from being slightly quiet and crackly. Went smoothly, replaced the dock connector, put it all back together and it's good as new now, assuming there's no signs of corrosion anywhere I couldn't see. The amount of water was very small, it got more moist than wet.
The screws are absurdly small. If you think the first two to remove the back panel are small, the rest are 2-3x smaller. I taped a piece of paper to my desk so it wouldn't move, and as I took screws out, I circled and labeled them so I knew exactly which is which, because that's important. A lot of piece inside Apple hardware are very fragile, you really don't want to force things, especially because if you break it, Apple's parts are generally quite expensive. Read through the guide before attempting so you know what you're getting into. Also, wash your hands before you start, it minimizes any oils you might leave behind.