[TheDon]

If the data is enough really depends on what you're doing.
If you're streaming from last.fm or spotify all the time you're going to eat through it. If you're just doing normal usage, checking email, browsing the web a bit, it'll be fine.

I'd say I'm pretty heavy on usage in terms of browsing (but I don't stream audio or video much) and I usually do about 15mb a day just with web browsing on the bus, and apps like facebook pulling data down, which is about 500mb a month.

It's really easy to track usage, there's a free app called netcounter which will log your data usage by interface, so wifi is kept seperate to mobile, and you can set alerts on usage levels, so if you're close to your limit it'll alert you.

Signal is fine, excellent in some areas, marginal in others, but about the same as the other networks.

Customer support has been great for me so far, accidently changed my tariff online because there's no confirmation just a click and it's changed and they changed it back immediately for me no hassle.