There aren't a great many toys still going strong from my childhood, but Lego is definitely one of…read morethem. I spent many happy hours building houses, garages (for my brother's Dinky cars), trains, and my own version of the 'Thunderbird' craft, although they didn't really look anything like the real thing. Not that I cared.
The big thing that has changed, though, is the change from just basic building sets to the huge range of specialised sets, with everything from space-ships to pirate ships, trains, cars, planes, and themes and franchises such as Indiana Jones, Atlantis, and Toy Story - to name just a few.
I must confess to being old school here, preferring the range of basic brick boxes and buckets to let children's own imaginations run riot, but I can see the need to compete in today's market-place with more commercially inspired sets. The key thing is that you have the choice. Basic brick boxes start from £6.50 (280 pieces) to £12.99 to the 650-piece Deluxe version, both of which seem pretty good value to me compared with many others toys these days.
The store is not that big, but there is more than enough choice, and the staff are knowledgeable and child-friendly. As the other reviewers imply, it pays to have a plan before you go in, lest you get tempted (or pestered!) to spend/buy rather more than you planned.
It's worth noting that there's a good website if you want to look in the store and then buy on-line later.