This plugin is a good start but is missing some basic features.
First, it's relatively easy and simple to setup. It gives you a fundraising gauge that fills up as you get donations.
I was able to setup a customized donation button easily.
There are some basic functionality features missing though:
1. There are color settings missing. The plugin allows you to change the colors of some of the elements but not all the ones that need to be changable. For example, you can change one of the progress bar colors, but not the other, through a color picker on the back end. I had to do quite a bit of CSS work to get the plugin to look right.
2. You can't add donations that were given offline. If someone donates from outside of the plugin, you can't update your fundraiser progress. There is a custom post type assigned to each donation and a page that keeps track of all of your donations, you should be able to "Add" a donation through this page, just like the posts, pages or other post-types.
3. You can't edit the progress bar. Similar to #2 above, you should be able to just specify what % your fundraiser is at.
4. The developer's website is gone. I don't think this is updated anymore.
Other than these issues, the plugin is simple, easy to use and works.