Personally, I consider anything in excess of 1000 kbps acceptable for a mobile network. Anything higher doesn't provide me with a perceptible increase in performance for what I do with my phone. What does make a difference is latency, the time it takes to actually establish a connection. By far, lower is better. Getting less than 100 ms on a mobile network is great. Less than 200 ms is probably typical. A much higher latency and the phone begins to feel laggy. The take home message is that the speed of a sustained data transfer is irrelevant if the time to actually start the transfer of each and every bit byte and pixel is ridiculously high.
As a baseline, here is a speedtest this morning done on wifi at home with a Nexus One. There is just no way this is going to be beat by a mobile network any time soon. And, unless things have changed recently, no home ISP in North America is going to beat these numbers: latency, 23 ms; DL, 14 Mbps; UL, 4 Mbps.
Yesterday, Ishikawa Tsutsumu put up another article in the Nikkei, this time doing a direct comparison of the iPhone 4S on AU and SBM. He does 10 separate tests at five locations around Tokyo and reports the average result. He concludes, unsurprisingly, that the phone just feels snappier with AU. The main reason wasn't so much a difference in throughput but in latency, which was five times higer with SBM (584 ms versus 106 ms on average).
However, referring to the graph on the first page of his article, the raw numbers weren't really that bad for SBM, at least outside of Shinjuku, where the world's busiest station routinely brings Softbank's network to its knees. But, rather than just steal a graphic from the Nikkei, let's consider Ishikawa's numbers in the context of each carrier's advertising.
DownlinkAt best, in a residential area of Tokyo, SBM delivered a 2700 kbps download speed, which is less than 20% of the advertised 14.4 Mbps. At the same location, AU clocked in at only 1300 kbps. However, this is 40% of AU's theoretical 3.1 Mbps maximum, which is actually quite good. Furthermore, at Shinjuku station, where the SBM iPhone averaged a usable but frustratingly slow 200 kbps, AU provided about 1350 kbps.
UplinkNeither AU nor SBM brag about their uplink speeds because, as far as I can tell, they are just standard 3G speeds under 400 kbps. Docomo and Emobile support 5.7 Mbps uplink, but don't expect anything remotely close to this in real life. The fact that Docomo depicts their Kanto hi-speed uplink coverage area not as a map, but as a list of areas, tells us all we need to know - that high-speed uplink base stations are scattered few and far between in a sea of 384 kbps uploads.
Getting back to the AU and SBM iPhones comparison, it is much more favorable in this department. Assuming a theoretical maximum of 384 kbps, SBM performs better than AU, delivering on average 35% of the advertised speed. AU is at 25%.
B-Mobile FAIR SIM in a Nexus OneFinally, here's what I got this morning (just one test) at home in mid-Tokyo. This is typical for me. The FAIR provides completely unrestricted access to Docomo's FOMA network. 172 ms, 2470 kbps DL, and 362 kbps UL.
The rest of the article
Voice CallsWhile out for the Super GT, he tried making calls from a rural, mountainous area in Tochigi. He placed twenty consecutive calls with each phone. After each call, he'd try and keep connected for 60 seconds. He had no problems with AU. SBM was horrible. It would take 50 seconds or so to connect, the phone would suddenly display "out of area," and he only succeeded in sustaining a call half of the time.
While driving between Ibaraki and Tochigi, he did the same and had much better performance from the SBM iPhone, though still not as good as with AU.
Of course he tried to used data during a voice call with the AU iPhone, which isn't possible with AU network.