Take it from a former economics student who graduated a few years ago - it's a bad idea on the whole. There are some good points, but the bad outweighs it. I'd say to only go there if you don't get any offers from elsewhere. Despite it being a Russell Group university, it's really not all that when comparing to the Economics courses at even UCL/Warwick/Nottingham. In terms of similar prestige, you'd be better off with somewhere like Leeds or Surrey and I'll explain why.
Lecturers are hit and miss at QMUL for economics - I'll acknowledge that some of them are excellent, but most of them really don't care.
You'll get an "academic advisor" who you'll rarely have any contact with unless they also end up teaching you for one of your modules. I struggled to get a reference from them for graduate schemes as I took a year out after uni to go travelling, and it delayed my whole onboarding process. Apparently you also have to go through them for everything, despite being closer to other lecturers.
Careers service at the university (especially if we're being specific for the School of Econ and Finance) is not that great. It's more on you to be more proactive. You'll learn more about CVs, cover letters, etc. from watching a bunch of YouTube videos that you would from their dreadful service.
A lot of students from my cohort who went to study postgraduate degrees, all aimed for "higher-ranked universities" (e.g. LSE, UCL, Cambridge, etc.) and treated QMUL like a bit of a stepping stone. Most of the students at QMUL are smart, at least from when I was there, because a lot of them had just missed out on offers for UCL/LSE/Warwick/Nottingham/etc. and had to go through clearing to get into the next best choice without the hassle of sorting out accommodation in another city (since most students there are originally from London, so choose to live at home).
Let me know if you have anymore Qs