I have a lot of respect for Dropbox as they've created an awesome product and user experience that accelerated its niche.

But as with Twitter i'm sceptical of the long-term prospects (and hence the need for an IPO vs a trade sale) of single-feature/protocol companies.

Nice liquidity event for current shareholders but why should the public invest here? The product is becoming more commoditized with time as well as being an ever more tightly integrated feature with hardware/OS.

Box seems to have a lock on the enterprise market which feels like the better long-term strategy than being a consumer/startup brand.

The stated growth strategy in the S-1 is rather meh. Post-IPO they might go further down the Evernote route and expand in all possible areas, diluting the core product/brand.