And one important benefit of WiFi. It doesn't eat into your data allowance.
Nor does viewing webpages or viewing emails. It's only downloading attachments/files/viewing videos etc. that actually count towards your data allowance. (at least that's how I understand it works, mine is unlimited regardless
)
It depends on the network but in all cases I know the internet and emails are included in the limit. Plus even unlimited wifi is not truly unlimited in many cases with fair usage policies (some as low as 250mb per month or less than 10mb per day). considering viewing some individual webpages can be well over 1mb and streaming videos etc are much higher. I always use wifi wherever possible, but then I am something of a data hog - according to netcounter on my android phone I have used well over 50gb (50,000mb+) in the year or so since I bought it (most of that on wifi). another factor is the 3g network is becoming saturated to capacity in some areas at peak times (in a similar way to how phones don't work at new years) and so the mobile networks are keen for people to use wifi instead of 3g etc. I am surprised fgw don't provide it on their trains-especially considering they sell the train as a more productive travelling option for business people!