1. You get 2GB of space for free, and the cost for additional space is reasonable.
2. Sharing files is easiest with Dropbox, particularly if you want to share files via a direct link.
3. The service seems reliable. I have not seen any downtime or other network problems.
My wife actually signed up for a Dropbox account today, so she could easily provide a large graphic file to a printer. What was impossible via email took just minutes with Dropbox.
If you’re interested in free, easy to use online storage, give Dropbox a try.
Extra Storage Bonus and Disclaimer: if you sign up via the above links, both you and I get a little extra free storage for the referral.