Though not in Freemake's class as far as making things simple, Fre:ac is generally easy to use. All my interface complaints are relatively minor. For instance, the GUI designers decided to use a smaller font and controls, which are hard on older eyes. Also, the icons only reveal their color when you mouse-over, and one dialog refers to high-quality as 0 and low-quality as 5. But it gets the job done, even if I have to squint a bit.
In my tests, fre:ac did a great job converting the file types in understands, and that's quite a few: MP3, Ogg, FLAC, WMA (including lossless--a hole in Freemake's support), and 44Khz/48Khz wave files up to 24-bit in word size. Unfortunately, there's no support for the APE, 64kHz/92kHz wave files, AAC, and Apple lossless files that Freemake Audio Converter handles. Fre:ac's major strength is that it allows you to precisely tailor the bit rates and quality of the output files. It may also be run from the command line which could be handy for some. On the other hand, it doesn't handle file name conflicts well at all--only giving you an option to overwrite the existing file.
Other nice fre:ac features are the ability to encode all songs to a single file (for easy editing, or non-stop medleys), and to generate a playlist and/or cue sheet to accompany the conversions. It also tracks the files it converts and keeps them stored in a database.
Generally speaking, most users will be better off with the easier, more versatile Freemake Audio Converter, but fre:ac has its strengths--especially the granular control, database, and command line.