The back end of the plugin works nicely and allows you to create forms easily, although the free version limits you to four fields plus a submit button.
Tables! The forms are output in layers upon layers of nested tables rather than using divs and spans. This makes it practically impossible to do any serious layout customisation and also makes the forms useless on responsive/adaptive sites.
Form fields are given fixed pixel heights and widths, which further limits your ability to customise the layout.
It's two years since the WordPress default theme became responsive, so it'd be really nice if plugins made an effort to output code that would work in the default theme at most screen sizes.
A quick W3C validation check shows errors throughout the forms, mainly because of the tables.
If all you want to do is add a simple form to your site I'm sure it'll do the job, but if you want full control over the layout or to have a responsive/adaptive website this isn't the plugin for you.