You need to be cautious about these kinds of questions and 
make sure you do not end up sounding bitter.------ I would 
never talk down about my former company, the boss, or my 
former co-workers. You need to have a good understanding 
about the job for which you're applying to turn this 
question into a positive one. 

It may be best to say that you really enjoyed many aspects 
of your job, then focus on how this new job will give you 
the opportunity to contribute more in a particular area 
that is key to the position.

go on to say that ur previous job was stable and assured 
and u have learnt a lot from it, now that u r ready to face 
new chanalges in the corporate world ...mention ur job 
nature along with it to make it more interesting.....

all the best to u all