Having ordered the modem I was a bit concerned to find from other reviews that it seems to be prone to over-heating. However I have fitted the supplied legs such that the power input cord is at the top, so that any heat will dissipate harmlessly and this seems to have done the trick, it certainly works OK and shows no signs of over-heating.
It was purchased for my neighbour, who was away on holiday when it arrived so I set it up at home, not using the CD-ROM but going to 192.168.0.1 from my web browser. The settings receommended by my ISP (same as my neighbour)were put in and it burst into immediate life.
Looking on the Netgear Website there seems to be no sign of any firmware upgrades, but I found that these were accessed from the modem setup function at the above IP address, likewise the user manual.
The fun started when I took it round to my neighbour's house and installed it there: the settings I had put in had changed (I suspect that this was due to it detecting a different phone number) and doing a hard reset caused it to get really confused. Fortunately I had backed up the settings for my home and this brought it back to life and after another trial it was brought into action for him as well.
In summary, if you know what you're doing - it's fine, but for a novice you need to follow the instructions carefully.