Whether this is nice or not depends on what message you want to convey with this graphic. If it is entanglement, then yes, the graphic reveals the complexity very well. If one wants to understand the debt situation in Europe, then no, this chart doesn't make it clear at all.
From the perspective of someone wanting to dissect the debt web, an enhanced data table is hard to beat.
The first section looks at the interdependency between the five troubled countries, collectively known as PIIGS on Wall Street. The additional debt owed to Britain, Germany and France are shown below. Notice that the original chart does not treat these three countries the same way as PIIGS: we do not know what the values are of the arrows pointing from these three into PIIGS.
Expressed on per-capita terms, Ireland stands out as the worst of the bunch while the citizens of the other four countries are bearing roughly equal amounts of debt per person.
I tried to come up with something more "fun", as below:
Here, I opted to use a small multiples chart to split the countries. In so doing, I accepted redundancy in search of clarity. Each amount is plotted twice once as a borrowing (red line) and once as a lending (black arrow).
It is immediately clear why Greece is the most urgent issue.
Perhaps the chart type is not as important as the transformations I did to the data:
1) All amounts shown are "net" amounts between any pair of countries. In the original data, there are two arrows between each pair. For example, Italy owes Ireland $46 million but Ireland owes Italy $18 million; this means Italy owes Ireland $28 million net.
2) All amounts are expressed per capita. Since the populations of these countries vary from 4.5 million (Ireland) to 60 million (Italy), the total debt cannot and should not be compared to each other.
3) Not shown here but I also expressed the net amount lent/borrowed per dollar of GDP. This is another metric that makes sense. The nominal GDP of these countries range from $0.2 - $2 trillion. The PPP GDP has a similar range.
4) One item I did not fix is the currency. Given the fluctuation in exchange rate between the Euro and US$, I think it may be better to express all the numbers in Euros.
A next step would be to include Britain, Germany and France.
Reference: "In and Out of Each Other's European Wallets", New York Times, April 30, 2010.
PS. Reader JF pointed out an inconsistency in the numbers on the chart. I revised the chart to fix this issue. In the current chart, one can read the information as: the average Portuguese owes Spain $5,453, owes Italy $141, while having lent $903 to Greece and $1,561 to Ireland. Each chart can be interpreted from the perspective of the average citizen in that particular country. (For details, see the comments below.)