I went to 2, very different experiences. The first one was in the tiny village we lived in at the time - church hall, cliquey Mums, etc. It was the same toys every time, just haphazardly laid out in the hall. I didn't enjoy it but DD loved it so we went every week (from 18m to about 2). Nobody spoke to me, not even on the first morning, except to take my £3. It was strictly one biscuit per child at the end, too. I found it a bit depressing and thought that was what all toddler groups were like.
Then we moved house and found a new group, and it was WONDERFUL. Different activities every week (nothing extravagant, but they had a rota of toys that were set out - Play Doh, puzzles, dolls, puppets, ball pond, cars, etc). It was in a hut with a baby area and a toddler area, outside space for the nice weather, a little kitchen you could see the DC from if you went to get a drink. Every session there was a craft activity, story and snack (DC could have biscuits and fruit, no limits!) followed by rhyme time. No pressure to join in if your DC wasn't interested, they could go and play if they wanted to. It was donation entry and I always tried to give whatever I could because it was so good.
I took DD every week from 2.5 to 4.5, then a couple of years later I took DS from 18m to 4. When I was pregnant with DS the people running it would entertain DD at a table for a bit while I had a sit down. They were angels! They did a Christmas, Easter and Summer party, and even during Covid they found a way to make the morning work safely. They were part of the church so occasionally there would be a story or a song about Jesus but it was fine and not rammed down your throat.
I didn't make lifelong friends or anything, but I didn't go for that. Some weeks it saved my sanity! I was quite emotional on the very last day...