In the first place, it should be pointed out that the job the Civil Service has is far more wide than the remit of any other company. It has to run the country. That is such a massive job that, realistically, it's impossible to get right 100% of the time or even close to that. I'm not convinced that anyone could do much better -- and indeed how many of those here have tried?
The Civil Service is, also, huge, at well over 400,000 people. This means that there will be a natural variation in ability, and certainly there will be a number of people who are not up to the job, at least not all of the time. That's to be expected. Job security might be higher, maybe even unreasonably higher, although this is changing of late due to the hefty cuts implemented by the current government.
Actually those cuts, while perhaps necessary, tend to leave fewer people to do the same amount of work -- indeed, in some cases even more work due to the hefty reforms of the Welfare System for example. It's not surprising that with fewer people having to do more work that mistakes slip through.
So, yes -- I think it's fair to say that the Civil Service is overall not that much more useless than the rest of us. And where it does fail the reasons are as much related to the job it has to do as it is to the people doing them.