I moved to Berlin almost 3 years ago. I'm an English speaker, don't have any EU citizenship/passport and didn't speak any German before moving here. Here's my perspective on the city.
In comparison to other big cities in Europe(Paris, London, Copenhagen), the standard of living does feel generally cheaper. Like
@sexualhelon said, you can find places all over the city to eat very cheaply and I feel that "enjoying yourself" is generally not super expensive. If you have a connection and can find a cheap flat here, you can sometimes get a room for 400eu a month. Sometimes less even. I will say that finding a cheap place, or any place for that matter, is so dependent on knowing people. The process of dealing with landlords and real estate agents is so brutal and you get treated like a second class person if
you aren't a white German.
Job-wise for people who only speak english, I imagine there is a lot of competition because there are a lot of people who move here with no real intention to learn the language and the idea that Berlin is this English speaking bubble. From my perspective and experience, it is not, and Berlin can be a quite unfriendly place when it comes to you and this topic. I would say that people here are typically unhelpful to foreigners and if you're in a position where you're trying to navigate the bureaucracy and need help with something, it's often that you will get lesser help or service if they figure out you can't speak the language. It's a situation that drives me crazy and I often have friends call the tax office, the internet company, etc. whenever I'm having issues with something.
The winter is definitely a tough one. Sometimes you'll have weeks where it's -5 to -10 but they aren't so long or often. What's the hardest is how long the grey persists - I swear sometimes you can go a month without seeing blue sky.
Berlin is full of culture, is incredible in the summer and you can be entertained 24/7 if you want to be. One thing I'm always impressed by is how this big, metropolitan city has all of the options that come with a city like it, but is also so close to nature, greenery and lakes. You truly don't need a car in the city or to get to any of the natural amenities I just mentioned and the bike infrastructure is pretty great too.
I'm super down for the city and I'll be here for a long, long time. I'm not aiming to burst your bubble with what I mentioned above, but I wanted to give you some realism based on what it's like from a foreigners perspective because I feel that people(myself included) have an idea of this 'utopia' that Berlin is. It's got it's rough edges and it will definitely put you through the meat grinder a bit, but I think a key to sticking it out here is committing to that and riding through it. I love the quality of life here and will be in Berlin for a long, long time.