Having used my Bluetooth-enabled phone (now the Nokia 6165i) to connect to the Internet using my Mac Mini and MacOS X 10.4, I want to relate my experiences.
As a dialup user, I found the cell-phone connection to be pleasantly faster, but not overly faster. Having been used to dialup speeds (and expecting nothing outstanding) I was pleased with the speed of the connection. Someone used to broadband speeds would be dramatically disappointed, but the ability to use cell-phone-based Internet connectivity anywhere can be a real asset.
I also found that the “modem” inside the mobile phone would react in strange ways at times, sometimes not responding at all, other times responding but refusing to make any connections, other times accepting input but not responding to input. Part of this may be due to bugs in the modem software – after all, the modem is not nearly as heavily used by the users as the mobile phone portion of the software. Part of this may also be due to lack of a strong data signal.
This brings me to what may be the worst drawback – the data signal is quite separate from the cell signal – so there is no indication of how strong it is or even if it exists in the current location. Thus it may be that when the data signal is weak, the modem will refuse to dial (the equivalent of not receiving a dialtone).
Much of this is hypothesis on my part about how the modem works – but I’ve found that MacOS X seems to be largely sound in its handling of the connection.
I’ve also seen the system go through a sequence (on the menu bar, starting in a connected state): “Disconnecting…” followed by “Authenticating…” followed by a continuation of the time spent online. I’ve attributed this to a possible loss of signal or a weak signal. It remains, however, rather disconcerting – but nothing bad comes of it.
The other bluetooth-based connections I use – one from the phone itself, and one from a Nokia 770 Internet tablet – are nowhere near this informative, so can’t say much about those, except the speed is the same (at least, it should be, eh?).
Also, my experiences with spontaneous loss of connection – for instance, when the phone goes dead! – have not been pleasant. Complete loss of bluetooth signal seems to be well-handled, but when the phone dies, there may be something else going on. Thankfully, this has not happened to me for some time, but I recommend not trying it :-)