Sun's stroke has been commented on here before and the similarities with the TI approach noted. However, it should also be borne in mind that even with his 'relaxed' stroke he had a lead of several seconds over the rest of the field and at the end of the race in Shanghai, after his amazing last 100 meters, he was ten seconds ahead of Ryan Cochrane, who is a top class swimmer with in my opinion a very nice-looking stroke, although admittedly not as nice as Sun's.
Sun is also a very fast 200 meter swimmer and clearly has a fantastic six-beat kick and grabs a lot of water with his long arms. the fact that he can lap consistently at under 30 seconds per 50 meter length with a stroke count of 27 or 28 sets him apart from just about everybody else in the world. The 1500 meter race will be one of the highlights of the London Olympics for me, and the finalists will probably all have to have swum below fifteen minutes.
So far this year only five swimmers have been below the 15-minute mark, Sun himself, Park of Korea, who is much shorter than Sun and may well not swim the 1500 in London but will probably concentrate on the shorter distances since he is competitive at the highest level at all distances from 50 up, the new star from Italy Gregorio Paltrinieri, Daniel Fogg of Great Britain, Yun Hao of China and David Davies, of Britain, who may be concentrating more on the open water swim.
A handful of other swimmers , including Chad La Tourette of the USA are capable of swimming under 15 minutes, but have not yet shown any form that makes them likely contenders for medals.
No doubt they're all beavering away, though, swimming thousands of meters a day.The position is probably somewhat like that in the sub four minute mile on the track . Once the barrier was broken there was an absolute avalanche of runners who could run under four minutes.
I think it's very likely that there will be a new world record in the 1500 this August, and it's most likely to come from Sun, but it's not an absolutely foregone conclusion.
The world rankings at swimnews.com make interesting reading: