Yep, it was fast. But that's all it was. They kept having stability issues and resized the v-stab twice to solve it. Further, nobody has ever described it as an agile or manuverable plane.
On the other hand, both RAF and LW pilots say the 109E was as nimble as the spitfire, and for the most part they were a very close match.
Basically the surface cooling schtick was a total and complete failure. Maybe if it had worked brilliantly the plane would have been adopted as "modern", but it didn't handle in a manner that LW pilots liked (I've got one book that says LW pilots disliked the way it flew, and have read quotes online that LW pilots disliked the wing loading on it).
Add to that the fact that 3 of the 6 prototypes took damage from landing gear failures (one while sitting stationary on the tarmac), and again it doesn't seem like a wonderful weapon.
Granted a lot of planes had teething troubles, but let me put it this way.
Would you want to fly the Gee Bee in a dogfight? What about the Me209? Both were designed for excellent top speed, as much power and as much speed in the smallest frame possible. Only neither would make a good dogfighter. Even the Me209 was acknowledged as a flop (designed to win speed records, with the idea that the fastest plane would be adopted for fighter use).
It would be like flying a typhoon against a Ki-84 in the game as it is now, only your typhoon only had 2x 7mm guns and 1x MG/FF that would probably jam as soon as you fired. Which plane would you rather be in, that typhoon, or a 109F-4? Slower, sure, but far far more capable as a fighter.
EDIT: The page you linked says "In 1939 the He 100 was clearly the most advanced fighter in the world."
It's not "clear" that this is the case. In fact it seems to paint a picture of a very fast but extremely troubled development. That doesn't make it "the most advanced" fighter in the world. It tried something new (the evaporation) and it failed. However, novel and extreme ideas were nothing new for the German designers (look at the 163, the 262, hell all the Luft '46 designs!!).
The entire bottom half of that webpage seems a bit biased. The predominant reason the He100 wasn't pursued was the engine. All DB engines were alotted for 109s [and 110s] (hell the 109s had to wait years for the DBs, they were designed for the 109s in the first place, or vice versa). Even the paragraph near the end stats Heinkel made it too complex, and couldn't put a Jumo engine in it, despite intereste from RLM in a non-DB-engined fighter (hell they ordered Fws by the thousands, anything using a non-DB-engine was gold, because DBs were hard to make and scarce).