Bulk import images & create nodes
The module Bulk Media Upload is the one that I have used in the past for that matter. From the module page:


  With Bulk Media Upload you can upload a bunch of files and a new node, taxonomy term, or other entity will be created for every file. The files are selected via a browser file upload dialog and can be stored in a file or image field.
  Also default values can be chosen for the other fields assigned to the new node.


I believe you will not have any difficulties, it is pretty straightforward. Also, if you come across some minor bugs, I have a couple of patches commited in its issue queue awaiting community review.

Alternatively, one can use the Feeds module to import nodes. That would be more helpful with existing files. It might require to list the files into a CSV file (for *nix systems copy/paste from terminal the output of ls /path/to/files).