I encounter some installer bugs/shortcomings. After about 30 minutes of trying, I was able to work out what the problems were.
Basically, the first installer/extractor (not the downloader) does NOT give any error message if it runs out of diskspace when extracting to the temporary directory. It just quits!
The real installer does give a 'error writing file' error but this is not that informative. Even more so since it appeared to me and I expect to many that the real installer would not need any more temporary disk space as the extraction had already been completed earlier. And in any case, we would expect the real installer to extract directly to the final directory. If it had not been for the earlier problem, I would not have realised the cause of this problem easily.
However for whatever reason the real installer still extracts to the temporary directory first and if you're going to do that you should either do a disk space check or even better, make a better error handler so it realises when it has a problem because there is insufficent disk space in the temporary disk and tells you.
Finally not a bug but it would be helpful if you could if you could provide us a MD5 or a CRC32 or some other hash so we can verify the downloaded file. If we are going to have to use the silly downloader, this is essential IMHO. I downloaded the file twice because of the above problem. Since I live in NZ where we have very low data caps, I hate having to download somewhat large files unnecessarily.