If the person you are asking about died more than 25 years ago, then it's OK!
If he/she died within the last 25 years, you need permission from the next-of-kin in order to see more than just basic facts.
A death certificate must be supplied (to prove date of death) unless the person died in service.
I have applied for a couple of records - one took just a couple of weeks, the other took 3 months.