I'm in a choir! We're singing in the closing ceremony of the Olympics We're a gospel-influenced choir of around 30, but have doubled in size short-term for this Olympics thingamyjig. No need to read music, the MD just sings you your part and you remember it, v v easy and a lot less hassle. Plus looks arguably better, not having to have sheet music and lyrics in front of you when performing.
I definitely recommend joining a choir to everyone!! There are choirs for everyone these days, what with branches of Rock Choir in basically every town etc. Are you looking for a classical choir? I would like to do more classical singing to get more sight-singing practice.
Singing is SO GOOD for your mental health, I swear. Do it! your voice will improve if you sing regularly, you'll get the knack especially if your MD/choir leader gives you a good warm up and exercises which you can practice at home. The good thing about a choir also is that you all blend together so really any minor mistakes get disguised, so there's less pressure and stress on nervous singers and therefore nervous singers' confidence grows!! So then there are fewer nervous singers and ultimately fewer mistakes! If you see what I mean. Plus the sound voices make en-masse is amazing in itself, sounds so good (getting a bit corny now, sorry! I just love it)
My choir is not at all serious, but that may be partly because he music we sing is so lively and non-traditional/serious. The choir sang at my wedding last month and they really got the party started! Rehearsals are so lively, loads of dancing and laughing. The classical choirs I've sung in in the past have always been fun as well though, choirs are really good from a social aspect and a good way to make new friends.
Do it! It's so fun. Especially as you're already musical, I'm sure you'll fit right in :)