Beginning writers are often nervous about joining a writing group, and yes, it can be daunting - but it's well worth the effort, for many reasons.
Firstly, once you've started showing your work to others, it will help build your confidence. The first time is the hardest, but the vast majority of writing groups are supportive, and you will be pleasantly surprised to hear the nice things they will say about your work. And if you take their comments for improvement on board and make a genuine effort to edit well, it will be even more encouraging when they see and point out how the quality of your writing is getting better over time.
As well as saying nice things, if they're worth their salt, they will also find the weak points in your work, and while praise is nice, constructive criticism is what's of real value - as this is going to make you into a better writer. A good critique group will highlight areas for improvement in your work in a sensitive manner.
There's no need to take criticism personally or feel that it's in any way putting you down. That is not the point at all. The purpose of criticism is to improve your skills, so a writing group will find areas for improvement in any piece of work - even if it's damn near perfect. Critique areas may be anything from grammar and punctuation to pace, balance, emotional impact, tense, dialogue, description - anything.
And of course, associating with skilled people who are also passionate about writing will give you the advantage that you can draw on their skills and knowledge.
So, if you've been making excuses for not joining a writing group - man up and get yourself down to one!