I normally judge a place by two criteria - in fact if it is a food place especially.
First - if it is a particular type of restaurant, say for example Spanish, how many people from said country actually go there (for me meaning how authentic the food is). Second - I also look at the popularity of the place by how full it is, or how many people queue outside before it actually opens. At Pizza Union,
seeing Italians queuing outside before opening obviously tells you something about this place - good things.
There are many Italian restaurants in London, true - and even a number of pizzerias, but precious few that you could actually say are very good, even less that are excellent. Pizza Union is one of the latter.
Why is it so good? Well, it does the simple things well - and fast - superfast. The restaurant and takeaway is ideal for a lunchtime crowd (though it's perfectly sized for dinnertime seating too), and so can knock out cheap and tasty pizzas in a matter of minutes. You may not even have enough time to think about what you're doing after eating. The choice is also classically Italian - Marinara, Fiorentina and Funghi are all present and correct - along with a few more interesting options. I recommend giving the Pizza Alla Cioccolata are tree - a heady mix of chocolate (Nutella, naturally) and mascarpone cheese await you - and a snip at just shy of £3 in price.
Now you know about it, keep it under your hat - remember, there are already queues forming as we speak...