I live in Brentford! I have found that many lifelong Londoners haven't even heard of it.
My recommendation for going out there is.... go to Chiswick, Richmond or Ealing instead! Seriously, I don't think that Brentford has much going for it in the way of restaurants, pubs, bars, etc., but that is strictly based on my own experience and I haven't tried all of the pubs yet! I agree with Vicky that Brentford is great from a public transport link perspective - where I am in Brentford specifically, there are several different bus routes, all within 100 metres of our maisonette. Also close by are two overground train stations (granted, they are on the same train line into Waterloo), and easy access to the Piccadilly, District and Central Lines. There is also access to a different overground train line from Ealing Broadway and still different overground train lines from Gunnersbury and Richmond stations, which are all close by.
There is a Brentford High Street rejuvenation project underway (which is gonna take a few years yet to complete!) but it should get a bit better. Also, with new build developments such as the GWQ, I am hoping for a bit of regeneration/gentrification.
OK, back to the question about recommendations for going out in Brentford, the very few places I do like to venture out to in Brentford are:
- The Old Fire Station - nice bar, pretty cool cocktails and they even have happy hour specials. The restaurant upstairs serves pretty good food too. Here is a link:
http://www.the-firestation.co.uk/- Fat Boys Thai restaurant (just a few feet down the road from The Old Fire Station) - this is a chain, but a small chain and the food is pretty good - they even have deep fried ice cream, banana fritters and apple fritters - both types of fritters served with ice cream, YUM!
- The Watermans art centre - great for indie type films, a bit cheaper than the mainstream cinemas.
http://www.watermans.org.uk/Before my husband and I bought a maisonette in Brentford last year, we lived in Ealing for a few years, and we still go back there occasionally to shop and to eat at our favourite local (nearly local) restaurant: Maxim Chinese Restaurant, located near Northfields tube station on 153 - 155 Northfield Avenue. My husband doesn't even particularly like Chinese food, but we both think Maxim is to die for. We are going back there in a few weeks' time and we cannot wait!!

Have fun!!!