Pros
Even if you've never done taxes before, the company will make sure you get up to speed. The training can be time consuming but it is thorough. You'll learn about how taxes really work and if nothing else, you'll be able to do your own tax returns and undoubtedly save money. You get to work in a semi-professional environment, most customers are respectful. You'll do tax returns, a bit of financial advising, and even some sales so this will look good on your resume. This works best for someone who has a flexible schedule (or at least some guaranteed 4-6 hour blocks of time to work throughout the week). You get to input your availability for each week and other than the last two weeks of the season, it's rare that you'll be asked to come in at a day/time you've marked yourself as unavailable.
Cons
This is a huge time investment, especially upfront. If you don't know enough to pass the Tax Knowledge Assessment online, you'll have to pay for and take a Tax 101 class with HRB and pass the final exam in order to be hired on. Each year you'll need 18 hours of continuing education to maintain your tax pro status. These can be done online throughout the year and you'll want to get them out of the way because in November/December, you'll have another 15-20 hours of HRB training. Finally, while you get paid a base hourly rate it's not much above minimum wage. First year associates can't earn commission and in subsequent years, your bonus will be based on being able to do lots of returns and getting repeat clients. How much you make depends on your office location, as the neighborhood determines the clientele.