Both I and a friend live in work in central London and have had a horror with O2's network - cutting out regularly at high traffic peaks. After weeks of denying this the CEO has finally said so - but not to his customers to whom he is still dissembling. Check out my friend's experience on:
www.02networklondon.com

I have been having similar difficulties with Vodafone on mobile broadband, but it is all the same thing - network bandwidth.

Lots of 'your cell is very busy' etc but in the end all this stuff must work.

Don't make me laugh! I ditched them years ago on account of how horrible their service was, and the fact it's until recently been tied to O2 was the biggest thing stopping me getting an iPhone.

Some of the apps on my Droid Eris do not work well when connected to Verizon 3G because it appears as if the apps are programmed to not let large amounts of data through. The youtube app, for example, doesn't play most videos when connected with 3G but works fine when connected with wifi. Also, you aren't able to upload videos of more than 3mb to youtube... lame. Looks like Verizon's solution to the bandwidth problem is to just limit the bandwidth.

To the first person who commented, i had the same problem as you although i upgraded my sim card and it all worked fine. unless you have the most up to date sim card, it cannot handle the requirements of the phone.

all was fine until this morning though but i assume that the number of articles similar to this one have something to do with it? i havent been able to receive or send emails sice 11.30 this morning and it is now 2.15.

I try and avoid using o2 data as much as poss and use wifi where I can, as I know it will be slow and, like an android who deceives his fellow shipmates by attempting to preserve the alien life form and return it to Earth.... unreliable.

This is not new news. I've had a nightmare with o2 over the last year.

Although having full reception and repeatedly replacing my phone, 02 have been unable to provide me with the service I'm paying for (My call go through to answer-phone, and I get constant call failures): A lot of there staff I spoke to agreed with me on this, but they were unable to re-imburse me in any way. Aparently if I get sevice sometimes, then they are poviding me with a service.

I've now had to buy a new sim card with T-Mobile and transfer my number (now also paying O2 a cancelation fee) for a service they were unable to provide). Magically this works perfectly now even thought certain 02 staff are sure it is not there problem.

I think the networks are going to have big problem as more of these data hungry devices become standard.