You'll be able to compute the SHA1 checksum of the downloaded file to see whether it was downloaded successfully, or if network issues or disk issues (or even attackers) prevented you from doing that.
$ sha1sum recaptcha-dotnet-1.0.3.0-binary.zip bfb3397d27c95e152d80529bd11dfdde35efdddd recaptcha-dotnet-1.0.3.0-binary.zip
It's not that useful for a single file you're going to unzip (and get errors) immediately anyway, but it could be useful if you host your own repository of downloaded files.
From experience, I can tell you how not fun it is to find the few broken files in a (Java) Maven repository of several thousand files without checksums.