Compatible: iPhone, iPod, iPad - iOS 3.0
It's difficult for me to review the Dropbox App without going over the value of Dropbox in general. Its the cloud service that reaches out towards desktops and Apps over the spectrum of devices today to bring accessibility and seamless communication to new heights. To me it's an integral part to my tech setup especially for these reviews and articles I write. A main selling point for me is Dropbox integration into Apps because it allows me to pick up files and progress through my Dropbox folder on my MacBook with the smallest effort.
Let me give an example of it's awesomeness. As me and my fiancee were leaving the house, we realized we forgot some pictures we had to show to an associate and didn't want to bring the MacBook. I quickly copied them into my Dropbox folder and synced my iPad up. Three minutes later (at most) they were conveniently located on my Dropbox App. The best thing about it is that it doesn't need Internet access, it downloads directly to your App and you can view these pictures without 3G or wifi.
The same works in reverse as it makes a fantastic photo syncing App that's free of charge. Pics you take on your iDevice can be uploaded with the Dropbox App and picked up on the Computer Application. The only feasible issue with this is that it takes up bandwidth and requires an Internet connection but these days those aren't terribly difficult to obtain.
Another big plus is the ease of access for documents that you may be working on carry with you over the air with little difficulty. Let me demonstrate with my writing setup over iPad and MacBook. On the Mac I have the ByWord App which is a fantastic word processor that saves in a simple word format. I save into my Dropbox folder and which I have synced with my AiWriter App on my iPad. With a simple Internet connection (at a cafe is usually my venue of choice) I can pick up where I left off without messy doubles or dragging and dropping.
This system isn't without it's flaws however. I lost about a dozen files I wrote in the AiWriter App that when synced somehow destroyed a lot of progress with my ByWord files. Prepared however, I backed it up beforehand luckily. This probably was the AiWriters fault and not Dropbox but therein lies the problem that with multiple sources linking to the Dropbox, one problem might wipe everything clean. Not to mention the service also does go down from time to time for maintenance leaving you out of touch with your own documents.
It's a sign of the times with cloud services quickly becoming the norm. Dropbox is a great, free introduction into what's possible with options for expansion with a monthly subscription. I have yet to take the plunge seeing as I don't use it for massive files. However this might change if I decide to upload graphic designs I have for ease of access (although at this moment I quite prefer syncing it through iTunes for now.)
Also to note, Dropbox is the best free way currently to actually have a free file management system on your iDevice at this moment unless Apple creates one in the foreseeable future (which I can't possibly imagine.)