That's not strictly true. You can compress, download and decompress. Also you can compress and upload, but not decompress again.
If you can't decompress once uploaded I feel that your 'What's New' section is misleading as it states the following:
Quote:
Integrated compression/decompression: Save a lot of time when transferring data. You can now use WISE-FTP to directly compress and decompress the data you want to transfer. The program supports the most popular archiving formats; e.g., .zip, .z, .cab, .gz, .tar.gz, etc.
It doesn't mention you can't decompress once you have uploaded the files.
This was the main reason for upgrading to the latest version, otherwise I would have stuck with version 3.
I use 1and1 and their file manager in the control has a decompress function, but I don't tend to use because it is slow and buggy.