Dropbox is stingier with its free storage than the competition but users can earn more through referrals and other promotions. The cost for additional storage is pretty high, but in terms of features and flexibility, Dropbox is hard to beat.
Dropbox is one of the oldest and most popular cloud storage services, and based on Dropbox reviews, it's clear this service has the cloud thing down pat. Top Ten Reviews says it's very reliable and lets you access your data from virtually anywhere on virtually any web-enabled device. A review by Macworld notes that the desktop application is relatively simple, with few features or options, while the web-based interface is very robust. The reviewer especially likes how easy it is to sync files across all of a user's devices that have Dropbox installed; folders shared with others sync across their devices as well. It saves deleted or older versions of your files for 30 days, so you can return to previous versions if need be -- and these files don't count against your storage limit. Like Microsoft SkyDrive, Dropbox garners an Editor's Choice award from PC Mag, which commends the "effortless" file syncing and points out it's one of the few services that work with Linux and Blackberry operating systems. On the downside, this cloud costs more than other services.
Dropbox supports a wide variety of devices and platforms, including Windows, Mac, Android, iPhone, Linux, Blackberry, and the Kindle Fire. It offers 2GB of free storage, which isn't much compared to competing clouds, but users can earn additional free storage by referring other customers; storage-earning promotions also pop up occasionally. Additional storage is pricey -- $9.99 a month for 100GB, $19.99 a month for 200GB, and $49.99 a month for 500GB -- but signing up for a year yields savings at all three levels.
Given its compatibility with way more operating systems and devices than the competition, Dropbox is currently the closest thing to a "universal" cloud storage service there is. Its reliability and strong sharing features should draw in power users or small businesses with lots of files to store and share. Excellent, yes, but costly storage options could deter some potential users.