I bought a $35.00 computer desk at Big Lots before my freshman year of college - and I sold it just last year - 10 years later for $20.00 and no trouble selling it!
It was built like a tank! It had seen its fair share of abuse (cups without coasters mostly) and the finish did not bubble, warp, or peel.
I had friends who bought a futon there, used it for their primary bed for 2+ years - and sold the frame for 1/2 of what they paid and the the other student buying the frame could get an IKEA mattress - and still come out better than buying a new one.
We bought our wrought iron / slate top - coffee table and end tables when we got married and they are still in brand new condition almost 5 years later. (We actually had to go to a different Big Lots to get one of the end tables - our local store was sold out.)
Their mattresses are the same quality as other furniture stores entry and mid-level products.
If you have young children that tend to climb on furniture when you aren't looking - I'm not sure I would suggest buying a sofa there - and really the only construction quality I would worry about are the seams on sofas with attached backs. If you DO buy a sofa - I would consider a scatter back model instead.
If I were you I would expect furniture from Big Lots to last 3-5 years depending on how heavily it is used. If it's furniture for a more formal living room and used only on occasion- I would think it would last 8-10 years.
As far their their dining sets you can see an obvious lack of quality in the chairs - I would be truly surprised if 80% of their chairs are still in one piece after more than 2 years. Also as far as the wood dining tables, I really don't know how much wear and tear they could take. However, I can see them holding up well if you use a clear lacquer or keep it covered with a table cloth and always use coasters.
If you looking for lamps etc - they all have to be certified by the UL to be sold in the US - so they have to meet safety requirements - so they'll be safe, and other than desk lamps - lamps usually hold up pretty well.
It's a good deal - take it for a test drive - sit on it - use it - feel it - and then go to a 'real' furniture store and compare the quality.
If you or anyone else it looking for a sofa that will hold up like granite - look for a Klaussner retailer new you. They are pricey - however they will hold up VERY well. Ours is almost 5 years old now and look brand new! Our neighbors actually bought the same exact model that we have (except different upholstery and color) because they claim it's the most comfortable sofa they've ever sat on! PLUS it is REALLY comfortable to sleep on for having guests over, days home sick, etc etc.
Hope this helps!