You can use options.display.max_colwidth to specify you want to see more in the default representation:
In [2]: df
Out[2]:
one
0 one
1 two
2 This is very long string very long string very...
In [3]: pd.options.display.max_colwidth
Out[3]: 50
In [4]: pd.options.display.max_colwidth = 100
In [5]: df
Out[5]:
one
0 one
1 two
2 This is very long string very long string very long string veryvery long string
And indeed, if you just want to inspect the one value, by accessing it (as a scalar, not as a row as df.iloc[2] does) you also see the full string:
In [7]: df.iloc[2,0] # or df.loc[2,'one']
Out[7]: 'This is very long string very long string very long string veryvery long string'