Maybe I am biased as a 3 employee. However, as anyone will tell you in ANY other organizations; customers can be a bit over the top in their reviews of certain things.
On 3 you do have 14 days to try the handset out, so if you don't like the handset or service - you can return the handset and the account will be closed.
Re: Network is expanding like other 3G networks. You'll find that the coverage is not that bad and those areas where there is no 3 coverage, then you have o2.
Re: Walled Garden. Although this still exists, there has been changes over the past little while. 3 offer mobile websites. 5MB (and 15MB) service of popular mobile sites for £2.50 (i.e. BBC News WAP, DigitalSpy etc.). There is Wireless Web which allows full internet access one being £15/mo and another being £45/mo.
Handsets are not bad now. I do have to admit in the past there has been some really really awful offers but now these seem to be in line with other networks. Nokia N70/80, 6280, SE K610i, K800i, MOT V3X and some LG handsets are currently being offered for sale.
Re: Priceplans. I would recommend the Direct price plans:
Direct VTT 500 (£25/mo)
300 min, 150 SMS, 25 MMS, 25 Video Mins, £5 inclusive download content/mo,
Direct VTT 1000 (£30/mo)
750 min, 150 SMS, 50 MMS, 50 Video Min, £5 inclusive download content/mo
Direct Text 950 (£25)
150 voice minutes, 750 text msgs, 25 MMS, 25 Video Mins, £5 inclusive download content/mo,
Direct Text 1400 (£30)
300 voice minutes , 1000 text msgs, 50 MMS, 50 Video Min, £5 inclusive download content/mo
These seem to offer a good deal for the money. However, the downside is that they are not available from 3rd parties like Phones4U / CPW etc.
If you have any Qs, just ask!