We saw American cruisers using Pocketmail in Australia and Malaysia and it looked like a convenient way to do email. There's no place local to me where I can look at the unit, but the specifications indicate that it can be linked to a PC, which to me would be an easier way to type email than the tiny keyboard of the sending/receiving unit.
You carry this unit to a local telephone and dial the pocketmail number. When you receive the signal, you put the unit up to the telephone receiver and it sends/receives email - dial-up without the connecting cord.
Personally, as much as I like the looks of the little unit (but that's more because I like ALL gadgets), I wouldn't use it. I have a small laptop computer in a Pelican waterproof case that I bring ashore when I need an internet connection to send/receive email and check our various bank/billing accounts (which apparently can't be done via pocketmail). When I can't dial up, I go to a cybercafe and send/receive email, but rarely access my online banking/billing records because I don't particularly trust the security in internet cafes.
I wouldn't be happy without a computer on board. I use it so much that I wear off some of the letters painted on the keys. I have charts on it so I can print one-time use harbor charts to keep in the cockpit (now, the flybridge) as we enter a new, unfamiliar harbor. It also helps in planning routes. And all my correspondence, records, etc.