I've said it before, but it bears repeating. A restaurant review can only be a snapshot of a restaurant on a single night. It may be the night that the restaurant produces the best food ever - it may be the night from hell when everything went wrong. There are a lot of variables that comprise the restaurant experience: good company tends to make meals enjoyable, an appetite will increase your enjoyment of any dish, good service and pleasant surroundings make everything seem smoother.

Apart from these more obvious variables, there are others. Most restaurants have more than one chef. The one who cooked for me may not be the one who cooks for you. Even the same chef will have dishes that he cooks better than others. I might happen to choose his best dish or I might choose his worst. Most menus carry a mixture of really good dishes as well as a few bad ones. It's possible too that a dish a chef does well 99% of the time could go wrong that 1% when I order it.

All of this means that each experience of a restaurant will be different. As a reviewer I try to minimise these differences by focussing on the room, the service, the prices, the menu, the wine list - all things that remain mostly unchanged from night to night. I'll tell you too what I thought of the meal on the night, but you should always bear the preceding caveats in mind.

This week I find myself in a different position than normal - this week I'm reviewing a restaurant that I've been to more times than I can count. I think my fist visit to The Unicorn took place in the early 70s in the company of my parents, and since Giorgio Casari took over from the strict Miss Dom some ten years back, I've continued to go there. What that means is that for once this is not a snapshot review, this one you can think of as a long exposure.

Like any restaurant The Unicorn has had its ups and downs. Chefs have come and gone and as a result the food reflected those changes. Some meals have been better than others over the years, but I never had a bad one, which is why of course I keep returning. There's another reason too that I keep returning: I know for sure that I'll meet a lot of people that I know there. In that sense it's something of a Dublin dining club for me. I've lost count of the lunches that began in The Unicorn, went on until evening and then finished up in The Shelbourne. I'm much more sensible these days, those legendary twelve-hour lunches are no longer on my agenda, but during the summer months, especially when the sun is shining, I love sitting at an outdoor table there taking the sun.

The Unicorn doesn't call itself an Italian restaurant, but its menu is largely Italian and so is its wine list. These days the menu has plenty of information on the provenance of the food - the suppliers of the meats, fish and vegetables are listed. I had lunch recently with Jane Stephenson, who organises conferences and talks, and she's a regular visitor to The Unicorn as well.

Inside it's always crowded, the tables are packed together and there's the hubbub of conversation giving the place an air of busy happiness. The closeness of the tables to one another is part of what makes the atmosphere in The Unicorn work: it ensures a casual, intimate feeling and the virtual certainty that you'll strike up a conversation with the people at the adjacent tables. The down side of it is that the tables are quite small, so if you have a lot of impedimenta in the shape of keys, phones, glasses and hand bags, the tables can become very cluttered.

Because both Jane and I were driving we decided on a meal with only mineral water, but the wine list in The Unicorn does repay careful reading. The mark-up is fairly high, but there are some interesting and unusual Italian wines listed that you won't find anywhere else. For this meal though, it was just two bottles of mineral water.

The Unicorn prides itself on the antipasto bar, which is a buffet laid out with Italian style hors d'oeuvres. While Jane chose the spinach salad to start, I decided to do the buffet. This has got better and better of late; the array of foods is almost bewildering. Here's a flavour of what you can find there. Roasted aubergines, roasted courgettes, prosciutto, various salamis, salads of all kinds, olives, fresh Parmesan, mozzarella, sardines and whitebait to name but a few. You can have this as a starter for €9.50 or as a main course for €16.50.

For her main course Jane picked the fish of the day, which was fillets of sea-bream. I was in an offal mood, so I had the rognoncini, which is a dish of calf's kidneys. Both of these dishes were very nicely presented and cooked and left us both contented with our lot.

Neither of us had a dessert, but we finished up with a coffee for Jane and an espresso for me. Actually, this was probably one of the better meals I've eaten in the Unicorn, but the truth is that even if it wasn't, I'd still go back again, such are the good feelings it engenders in me. The Unicorn isn't cheap: this two-course lunch for two with no wine came to €74.85, but for the occasional treat I'll happily pay it.