In my blogpost on Feb. 26th, I compared Dropbox's numbers to those of Box and wrote that the IPO valuation of Dropbox should be at least $10B comfortably.
Then when Dropbox first priced its pre-IPO shares at about $7B pre, many journalists shouted out "See!? The previous private valuation of $10B was a joke". I commented publicly on my FB that I was a bit surprised. I said maybe they wanted to allow for upside post-IPO.
Then they adjusted to $9.2B the day before IPO, which is closer to my estimation but I told a few friends that there should be at least 15% upside post-IPO. A VC friend agreed with me and we placed a bet on how much upside it would have. He graciously took the lower-upside scenario but said he'd buy on first trade and if it goes up he's happy to use the proceeds to buy me a round of beers.
Now the first day closed at 40% up and $12.4B market cap. I was right from the beginning.
Bottom line: Unlike Snap, Dropbox is a story of numbers (cash flows, real growth, etc).
It's always easier to price such a company (as is seen by the stability of its share prices throughout the first trading day) than a shot-in-the-future type of companies like Snap.