This is a question where the answer will depend on what type of art class or course you are looking for. I have my own ideas of what you should see in a good art class or course, which I will share with you:
It Should Challenge You – Even a basic course should challenge you in some way to think in new ways and try out new things. I know that for some learners there is an uncomfortable feeling in being challenged but in my opinion the best classes are those that take you slightly out of your comfort zone.
Feedback – One of the reasons you are taking a class is presumably to have access to an art tutor/teacher with experience. I have seen a few art classes where learners have had little or no feedback from the tutor/teacher on their work. There will always be learners who don’t want or need much feedback, yet there is usually something that a learner can gain from feedback.
Opportunity to Share Work – Although many beginner learners are very reluctant to share their work, there is so many advantages in doing so. Ideally the art class or course will have some type of ‘critique’ or ‘plenary’ where the group gathers to show their work and talk about how they created it.
Some Scope to Follow Your Own Interests – This will depend very much on the type of course, if you are following a syllabus then there will be restrictions. Even in this case the best courses or classes I feel are ones where you can follow a theme or demonstrate a technique but still follow your interests. I remember being on an embroidery course where everyone had to do the same. I remember wanting to make a belt (but using the stitches I’d learnt) but was told I must make a hanging ornament. I did make a belt outside of the course and had little time left for the hanging ornament.
Identify Your Goals – Ideally you will have thought about what it is you would like to achieve before you start on the course. A good art course will identify some goals for you to work towards.
Ability Levels Roughly Similar – Some art courses have learners of wildly different ability levels on them. There is nothing wrong with this as the beginner learner can learn much form the more experienced. However I do think it is best to have a course with roughly the same level of experience in all learners so you can learn together at the same pace. This will be hard in a subject like art, but try to find out the general level of experience of those on the course.