As shown above, your data is exported as an HTML file. The backup includes any files that you uploaded as well. However, the HTML is not always formatted as cleanly as one might like. It works best with material you created using Springpad's own editor, and works the least well with heavily formatted material pasted into Springpad (e.g. things like tables).
As you can see below, more pedestrian entries come out just fine.
So, at least for now, don't go too nuts with flashy posts in Springpad. That said, the backup feature gets the job done; and you need not fear lock-in.
