Advantages: One stop DIY shop. Very helpful staff
Disadvantages: Is putting the local hardware shops out of business
I think B&Q is great, but before I get carried away, I also think the local hardware store, which is becoming a thing of the past, is fantastic as well.
You will find practically anything here for the house and garden from a washer for a tap to a full blown kitchen.
Primarily B&Qs purpose seems to be for the DIYer, but they are now moving into more stuff like home accesories.
What is impressive about B&Q is that it is logically set out, though when you first go into a store, you should ask a member of staff where the things you want are situated - most of the staff seem to know the store (and the stock) like the back of their hands and this will of course shave a couple of minutes off your shopping experience - I am sure the other guys will agree that shopping involves: knowing what you want; getting straight in, purchasing and getting straight out again.
Don't expect the nice pampering you might get when you go clothes shopping. You might also get the occasional member of staff who will look at you as if you are stupid, when you ask a question. Apart from the idiot know it all, what you should get (from my experience) is a bunch of helpful people who not only know their stock, but also seem to know about DIY and house maintenance.
Now I put this fairly and squarely down to the fact that they actively employ older people - to cut a long story short you can't beat experience.
I have been on both sides of the counter when it comes to retail, as a consumer, as a shop floor worker and as a manager. As much as what I am about to say might sound ageist, you cannot beat the help of an older person in retail.
As much as I like the 'one-stop' nature of B&Q, I will always wherever possible try to support the local hardware store, although there is none near me anymore, so B&Q has to be the choice for me.
Summary: A great place to get all you need in one go.