Went in there before Christmas with the girlfriend. Walked out empty-handed.
Went in there on their 25% off sale just last weekend (and it was 25% off the prices they were normally charging not a "sale-to-put-things-back-how-they-were-priced-anyway"). Walked out with £50 worth of stuff but - to be honest - that was more impulse purchase than anything else (we were both checking with each other "if it's okay to buy that" because we knew we were just impulse-buying and could get those films cheaper anywhere else), and they sell a lot of foreign movies that my girlfriend likes (we bought three foreign movies and two dvds-of-a-series). We had put a lot of stuff back on the shelves when we weighed up the value of it. There were no queues that time, either (which is unusual - they had some atrocious queues before Christmas, even weeks before, and not enough staff - enough to make me walk out without even looking because I wasn't going to queue through that for an impulse buy).
And what value do the staff add? None. It's basically a DVD and music library - flick through, get what you want, take it to the counter. What's the advantage over Amazon, etc.? Immediate availability of the most popular titles only (for years, they didn't know what "Just Good Friends" was when I was trying to buy it on DVD, didn't have it for years, and could only try to order "Just Friends", some American comedy movie).
Same as Comet - products on a shelf, pick your product, staff are useless, most things not in stock anyway, and pay over-the-odds to get what you can get elsewhere. It's basically a big supermarket for non-perishable items that's more expensive and more hassle than the alternatives.
Notice, also, that WHSmith have several large stores that have no DVD's at all on shelves (one in Watford has only two little turntable shelf things with about 20 unique DVD titles on there, most of them kids' films). They know they can't compete. About the largest WHSmith DVD section I see nowadays is the one near the BBC which sells, surprisingly, mostly BBC documentaries and comedies. They're quite good at knowing what sells on impulse and they've cut right back from the days when you had walls of DVD's in there, the same as they used to have shelves of ZX Spectrum tapes back in my youth but now don't sell videogames at all.
I'm not shocked. All these big, established chains wanted to do what they've done for 90 years and not change. They didn't stand up for the consumer (hell, imagine if they'd said we only sell DRM-free disks? That would be a kick in the teeth for their suppliers and also have consumers feeling they were on the same side). They didn't innovate. They didn't compete. They didn't change when they knew they couldn't compete. They just drive themselves into the ground, blinkered to reality.
Go find a sheet-music shop. It'll be some tiny back-street affair with a few instrument in the window, some adverts for tuition, maybe tutorials and CD's, spare parts, you name it. Because they know how big the market is, and what they have to do to keep afloat.
Now find a CD shop (HMV was pretty much the only one left - Virgin Music is dying off too and has been for years). They are IDENTICAL to how they always were, even down to rifling through bins of CD's put into four genres, with high prices, huge premises, and useless staff who got the job because they "like listening to music" (so, only about 99.9% of the population to choose from then). And nothing much else. No online shop, no burn-to-CD service, hell, they could have stuck some instruments in there and set up a £5-a-go recording studio for teenage group and try to sell the instruments on the side, but no. They didn't even TRY to change. They didn't even try to engage their core market (seriously - these music-fans wouldn't be interested in an instrument section, or some band trivia, or even indie band gigs in-store?). I have no doubt they made a lot of money for a LONG time, but it's hardly shocking that that came to an end.
I actually chose HMV as the "next to go" when I was shopping in there just after Comet went bust. I don't think Dixon Group will hold the monopoly for long, they just held out for longer but have the same problems as Comet did. WHSmith has held on pretty well in my opinion, but that won't last forever given the changes I've seen lately. I'd probably go for Pets At Home next - can't see how they make money from the occasional sale of a rabbit and some overpriced dog-food (and, hell, you can't even get a kitten or puppy from them!), especially with their usually-huge premises. That or Hobbycraft, but Hobbycraft covers quite a diverse range of people and products.
To be honest, wouldn't be surprised to see one of Wickes, B&Q or Homebase go soon, either. Overpriced tat and dumb staff in huge premises.