How miraculous was the miracle on the Hudson?
This would be an extremely difficult question to answer without being opinionated, but I'll give a try. As part of the investigation, the NTSB, along with other agencies carried out a number of tests on simulator, where pilots were tasked with either landing or ditching the aircraft.
There were three different scenarios contemplated:


Normal landings on runway 4 at LGA, starting from an altitude of 1,000 or 1,500 feet on approach;

Attempted landings at LGA or TEB after the bird strike, starting both from zero groundspeed on takeoff from runway 4 at LGA and from a preprogrammed point shortly before the bird strike and loss of engine thrust, and;

Ditching on the Hudson River starting from 1,500 feet above the river at an airspeed of 200 kts.



In the first case, all the landings were successful, which is not surprising. However, in the second case, landing was successful in (slightly) more than half the cases, but only where the response from the pilot was immediate (i.e. there was no delay between loss of thrust and decision to return to airport).

Regarding the second flight scenario, 20 runs were performed in the engineering simulator... Five of the 20 runs were discarded because of poor data or simulator malfunctions. ... In eight of the 15 runs (53 percent), the pilot successfully landed after making an immediate turn to an airport after the loss of engine thrust.

In the one case where a (35 sec) delay was included, the landing was not successful.

One run was made to return to an airport (runway 13 at LGA) after a 35-second delay, and the landing was not successful.

It has to be noted that in all these cases, the pilots were already briefed about the manoeuvre they were about to perform.
The third series of tests were conducted to see whether the pilots were able to achieve the target flight path angle of -0.5$^{\circ}$. Only one Airbus test pilot was able to come near that value. From the report:

Regarding the third flight scenario, a total of 14 runs were performed in the engineering simulator in which pilots attempted to touch down on the water within a target flightpath angle of -0.5°, consistent with the structural ditching certification criteria. Two of the 14 runs were discarded because of poor data.
In 11 of the 12 runs, the touchdown flightpath angle ranged between -1.5° and -3.6° (the touchdown flightpath angle achieved on the accident flight was -3.4°). In 1 of these 12 runs, a -0.2° touchdown flightpath angle was achieved by an Airbus test pilot ...

From these simulations, it appears that the flight crew took the correct decision to ditch in the river. Also, we have to take into account that taking decisions in real world under extreme stress is quite different from taking them in a simulator. The report notes that,

The one simulator flight that took into account real-world considerations (a return to LGA runway 13 was attempted after a 35-second delay) was not successful. Therefore, the NTSB concludes that the captain’s decision to ditch on the Hudson River rather than attempting to land at an airport provided the highest probability that the accident would be survivable.

Another thing to note is that there was no simulator training to the pilots, either as part of the airline or manufacturer program. In fact, the dual engine failure scenarios were presented only at high altitudes.

Ditching scenarios were not included in either the US Airways or Airbus simulator training curriculum.

A similar incident happened in case of the Scandinavian Airlines Flight 751, where the pilots successfully landed the aircraft without any fatalities.
One also has to consider the other issues in ditching in water (like the associated visual illusions). From these, we can form the opinion that a sizeable minority of airline crews would have ditched the aircraft successfully on the river after bird strike so as to enable rescue. As for zero fatalities, it would be near impossible to say that with any certainty, as there are too many factors in play here.