I'm not sure it's the ideal place for everyday shopping, but it sure is an extraordinary food court.
The concept is very different from the Boqueria, where you sit down at one of the bars to eat - here you can either do that but you can also pick your food from several places and the wine from others and just sit down anywhere.
You could get, for example, some salpicon de mariscos:

From 100% Galician, sustainable, day boat vendor
Lonxanet, where the decoration is also food:

Or Daniel Sorlut oysters:

Or maybe some jamon:

And have it with wine from
Pinkleton, who'll pour anything from 2 Euro whites to 29 Euro glasses of Vega Sicilia. Their decor is convincing:

There's also another wine vendor who'll sell you CVNE Imperial Reserva for 12 Euro for a half bottle, and many other options.
Open continuously from 10am to Midnight (2am on weekends) and a huge, if soulless success.
New Nordic - a cuisine that is highly compatible with DSLRs.