‘Is law firm culture really a thing?’

1) Is law firm culture really a thing or is this just a marketing gimmick?

Yes, the culture between different law firms is palpably different. All law firms will have a different mindset in terms of things like concern with pay, work-life balance, friendliness, diversity, the importance of hours targets, development, and (most importantly) not being a total dick.

Two caveats:
(i) You shouldn’t blindly buy in to marketing hype that says “we have a great culture!” with no further explanation.

(ii) Culture within each individual team in a firm differs just as much as between law firms. A tax team will have different set of priorities to a private equity team.

2) And if it’s really a thing, how much weight should I give it when making a decision?

Some, but as a law student you’ll have a poor grasp of the facts. This isn’t a slight on you – you only get a sense a culture from working with (or across from) those lawyers. You should get a general idea from discussions online, but ultimately it’s up to you how much you should take it into account alongside things like pay, hours, how likely you think you’ll be to get a TC, etc.

The gold standard of information gathering would be to talk to lawyers in the teams you’re interested in (NOT just HR teams from that firm!) or at least people who have worked with them.

Culture is a term used to capture a few things, some tangible and some not so tangible. Some of the most important parts of it are the approach to work-life balance and the likelihood of encountering difficult personalities. When looking in from the outside the approach to work-life balance is the most obvious indication of a firm’s culture, as it’s difficult for you to work out other parts of it without experiencing it yourself or talking about it with people who have.

In very general terms, firms that demand very long hours (so those with billable hours targets in the region of 2000) will have a “high-performance culture”, which tends to mean that the work is prioritised above all else. People may be nice and respectful in a lot of ways, but if you fail to meet the high expectations then you won’t last long. With this pressure comes massive pay, so it’s up to you as to whether this is what you want. Generally every firm that pays above ~£130k to NQs will fit into this category, though there are exceptions (and in respects culture is also team and department specific within firms). Clients have extremely high expectations when dealing with these firms and they will demand the world from you, and your supervising partner will make sure you give it to them. If you want the long hours, big deals, big money and you can deal with the stress, go for one of these firms.

Firms that advertise their respect for work-life balance will also tend to have a more friendly culture that creates a bit less pressure. In London, these firms will probably have billable hours targets in the region of 1600 or less. They are less likely to have an “up-or-out” attitude, so if you make the cut and qualify as an associate you will have security unless you bill well below targets or management takes an axe to your practice area. Generally the people will be a bit more relaxed and everything will be a bit less stressful. You will earn less but you will sleep a lot more, though you will still be working at a London law firm, so don’t expect a stress-free 9 to 5.

This is all a generalisation and don’t forget the importance of practice area. You could end up with a more relaxed life working in real estate in the magic circle compared to working in corporate in the mid-tier. There are also bad personalities everywhere, so even at more relaxed firms your life could be hellish if you end up working for a very difficult partner, and vice-versa.