>>396268German here.
>Do you think it's worth joining one?Yes, I mean, what's the alternative? Being a content creator on the internet? I'm sure that has their time and place too but if you don't do that you should get organized. Remember that most organizations only demand a very low due, if it's a cadre organization you can not however just be a formal member, they will expect you to participate in activities.
>what has been your experience with IRL leftist organisations?I'm a member of my country's communist party, and so far my experience within the party is mostly positive. It's a serious Marxist-Leninist organization so you won't have to deal with weirdos and sex pests, most people are dedicated and not LARPers, the theory they produce is on a good standard, and my interactions have largely been very friendly. However, when you are out on the street, it's hard not to sometimes think about taking the blackpill. The people I talk to on the street are largely just concerned with bullshit issues like legalization of cannabis or ask we whether we would raise someone's income tax or not. Then, some people are just apolitical and don't care, and some are overtly anti-communist telling you to go back to North Korea. Old women think you are trying to sell them something. In unions, there is a petit-bourgeois atmosphere of labor aristocracy, they just want a raise, and that's it. No class consciousnesses and the union leadership since the Cold War consists of handpicked reformists and anti-communists. In enterprises, you risk getting fired once you start trying to create a communist cell. It really is an uphill battle but I will never give up.