Mobile banking would appear to be way more popular than anyone suspected then, with 12m customers in the UK on Monitise's product alone... except that number doesn't quite ring true.
Monitise don't list clients on their site, but if you backtrack through press releases it looks like they currently have RBS, HSBC, First Direct and Alliance & Leicester offering the client as a trial or full product. First Direct have around 1.2m customers, but I've struggled to pin down good figures for the others - however the UK as a whole reached a record 18.1m online (Internet) banking users in 2006 (according to APACS), split between all the personal account offering banks: major high street banks (Lloyds, Halifax/BoS and Barclays do not use Monitise) and a few minors (again, only A&L use Monitise). Monitise said after RBS signed on they could potantially access 35% of Link-compatible cardholders, which is 95% of the UK's population of 58.8m (at the last census in 2001)... or about 19.5m.
So Monitise appear to either be doing exceptionally well at getting signups - with more mobile users in half a year willing to pay 20p+data charges to get a balance, than all the partner banks have persuaded to use web clients for free after 10 years of UK online banking - or they actually meant "potential users" and their real download figures are too low to mention in such a triumphant press release. Use the client and tell me which you think is the case (or of course read some of the reviews if you can't).
The problem is, mobile banking could be great and I'd definitely sign up immediately - if I didn't need to go through an 11 step signup process to get a terrible UI, to be charged 20p to know my balance just went down 20p (and not much else, though more features are promised). What's wrong with a nice simple phone thick client which uses online logins to let me do everything i can do in my browser - check my balance, move money around, find out if payments have gone through, etc? Shouting so loudly about the wonders of mobile banking and then failing so badly to deliver what customers might want just poisons the marketplace for other mobile applications, and denies users useful functions. The mobile experience is painful enough right now without the additional burden of poor app development.
Bootnote: I meant to post this some time ago but had trouble researching useful banking stats. It appears that in the meantime Morse/Monitise's PR firm have done an exceptional job at spraying the release all over the web and yet been less efficient at correcting the key highly misleading stat. How strange... still, if I understand right, there will need to be full disclosure of finances, users etc before the listing on AIM so no doubt we will all be the wiser soon.