Yes, I forgot to mention their drawbacks.  Now I
will speak about this.

For Perl, its complicated syntax is well known, it  sometimes
becomes annoying. Two students in my lab studied
some weeks Perl, when they come to solve real problems,
they still use Excel! There are two things in Perl I hate most,
the first it the using of $@ as variable prefix, the second is
its way of passing parameters to a function, they are quite
annoying, at least for me. There are also a number of other
thing I find difficult to use, you can imagine how difficult
they can be for people have little programming experience.

For R, if you have a look into it, you will find it has a very
strange syntax, some place the syntax is so strange that I
have no idea why they should be like that, for example,
if "x" is an array,
dim(x)<-(2,4)
will change the shape of "x" to 2 times 4.
Do you like this kind of syntax?
The worse thing about R is, it is very inefficient both in
time and memory.

About Java, I don't deny that Java is good, I just feel that
it's not as fast as C/C++, and not as convenient as scripting
languages. So it's for sure that it is not suitable for some works.

Now I think my answer is more complete.