One of the current ad campaigns promoting 3G broadband promises "the fastest, most reliable mobile broadband in the galaxy", and depicts a 3G-enabled USB flash drive flying through space at lightning-fast speeds. But I doubt very much that anyone would be able to get a reliable 3G signal on Jupiter if I'm still struggling on Earth.

To be fair to Vodafone, we reviewed the company’s USB Modem Stick last month and found the service excellent in most of the areas we tested it. We tried in across central London (excellent coverage), in Hampshire (excellent) and in Preston (excellent).

However, it's probably fair to say I have unrealistic expectations of mobile broadband - what's most important to me is being able to access the web on the train into work in the morning. In that respect, Vodafone's service is patchy, to say the least.

But it was far superior than O2's current offering, which I'm trying out at the moment. I can't get online during my train journey, and I'm struggling at home too (despite O2's postcode checker suggesting I should be able to get decent coverage). That's just my experience, of course – colleagues at PCA who've tried it say coverage is good in other areas.

The problem is, everyone's experience with mobile broadband is different, so it's impossible to provide a definitive rating for the mobile broadband coverage of any operator. What we really need is some sort of try-before-you-buy system, where consumers and business travellers can try out a mobile broadband product in the areas they'll need it the most before signing up. That's particularly important given that many contracts are for 18 months, while those who choose to pay by the month have to pay for the cost of the hardware.

But the prospect of Vodafone, O2, Three and T-Mobile handing out thousands of mobile broadband trials with no guarantee that users will sign up seems as unrealistic as my demand for high-speed internet access on the train. Let us know your experience with mobile broadband, and maybe you could help people in your area pick the right deal.