I continue to use MPFreaker despite some annoying issues, even in version 1.5. However, it does what it is supposed to, and pretty well for the most part. MPFreaker allows the rather painless retrofit of lyrics, artwork, and other ID3 information to your audio file collection. For me it has worked well with both MP3 files as well as M4A files (i.e. apple lossless).
Unlike downloading artwork from the iTunes store, MPFreaker downloads artwork from around the web. As a result, it's potential reach is much higher, but the quality of the artwork is probably more variable as well. However, if you have a large collection (and anything that can be even remotely construed as obscure), the iTunes artwork servers are unlikely to have it, and MPfreaker may have a better shot at retrieving the info.
That is not to say that MPFreaker is incredibly successful. It too struggles to find artwork and other info sometimes. Then it's your opportunity to search google, amazon, and discogs, among other sites for the missing data. In these instances, I use MPFreaker to identify which albums are missing what, find the data online, and then paste it in via iTunes.
Another benefit of not using the iTunes store is to bypass the new artwork storage process that Apple has introduced as of iTunes 7.0... instead of storing the images in the song files themselves, the pictures are now stored separately in a folder for art. From a space/efficiency point of view, this is the right approach... Trouble is, many music/streaming devices out there do not yet have the ability built-in to read these folders, so I prefer to bloat my songfiles for now.
Unfortunately, every time the application hangs (and it does happen from time to time), the preferences file is obliterated and your registration information is lost. Frankly, re-entering the information over and over is getting awfully old. Perhaps the best approach is to make a copy of the preferences file so that I can simply copy it over the corrupted preference file.
While we are on the topic of improvement potential, how about a multi-threaded application that takes advantage of the fact that most of us have high-speed connections to the internet? The present app goes through the list one song at a time, and a review of IP traffic in that time shows almost no activity. By sending data requests for 10 songs at a time, MPfreaker could boost its output 10x and have zero impact on the host computer or its internet connection.
I bring this up because the average songfile takes 5+ seconds to process (never mind the time it takes to make "deep searches") and neither the CPU nor the Internet connection are the bottle-neck. Go over a couple of thousand files and your machine will be working on the problem for days. Combine that with stability issues, and you have a recipe for unhappiness. As I write this, MPFreaker is hung, again, while "Scanning Directory".
Another feature request that I would find very useful is if MPFreaker could hunt songfiles that have bitmap images in them and to convert them to JPGs at a set quality. Apparently, pasting images via iTunes may result in a bitmapped image being appended to the song file, so a lot of space gets wasted that way.