Yes, they do to a certain extent.
The pros of attending a group lesson are that it’s usually cheaper (at first), and can be very fun. Some people prefer it, as they can see it as a social activity to not only learn, but to also make friends and bounce ideas and discussions off of each other.
It’s certainly a great way to meet people and share ideas.
The cons are that you will not progress as quickly as you would if you have one to one lessons. There are typically only 1-2 teachers in a group session, and if there are 10-20 of you then it would be difficult for the teacher to get around all of you to help. Everyone also learns at different speeds, so if you are advancing quicker than the rest, then they may be holding you back. Or if you are behind the rest of the group, then you may struggle to keep up, and it’s possible that you get frustrated and quit.
It also probably ends up being more expensive, as you would have progressed to the same level much quicker with one to one lessons, and you wouldn’t have spent as much. For example, if you were to pay £10.00 per hour for a group session, then you may be lucky if you actually get about 10-15 minutes of the teachers time. However, if you pay £24.00 per hour for a personal tutor, then you are getting a full 60 minutes of their time.
My advice would be to always have a personal tutor. Pretty much everyone that wants to learn piano wants to learn quickly, and get to a good standard as fast as they can; and the only way they can do that is to invest in personal tuition. Typically you would have a lesson each week, but if you are worried about the cost, then once every two weeks would still get you further than group lessons.