I like that I can send any file type...not only Quicktime movies...but audio files or project files. I'm not limited only to upload video for clients to review, I can get them elements of the projects as well. And I LOVE that we get notifications when a client accesses and downloads or views what we post. Because then you can either remind them when a lot of time has passed when you posted it, or prod them for notes if too much time is passing, and the clients can't lie and say "Oh, i haven't seen it yet."
I like that I don't need to tie it to clients. I don't need to authorize a select few people to "collaborate" with. I have my regular clients, and then I have the occasional one-off clients that I need to send things to...and I don't need to add them to any collaboration list, I just add their email and they can see it. They can also forward the email to other to view.
And I can use it to send my mom and dad a quick video of the kids without posting it to YouTube...give them something to download.
I like that things remain on the server for a specified time of my choosing. Either the default 90 days, or indefinitely. Up to me. As I have clients who consistently need to access a file, who don't download things. Review collected by and hosted on G2.com.