Pros
I think working here is a great place to get your feet wet with taxes and accounting and learning how to deal with all different types of client. There will never be a time that you will really be left without help since they have many tools and resources for information as well as people spread all across the city with a wide knowledge base and some with 20+ years of experience. Honestly speaking it will be the manages and other staff members that will make or break your experience. I've worked in 5 different offices over the years each one has a similar H&R Block feel to them but it is the people you work with day in and day out that will make going in to work during the most stressful time for most people worth while or make you that less happy to show up to work. That being said theres always opportunities to fill in at other offices during the tax season and you can always request a transfer for the following season.
Cons
Don't expect to be moving very fast within the company, as most junior tax professional contracts are only for 4 months, it takes two or three times as long to get the knowledge and experience to the same tax situations as you would in an actually accounting firm. As you slowly inch up the company you will soon realize that the pay is laughable and commissions bonuses are the only thing making up for it given that you get the hours and returns to boost your pay.