Pros
H-E-B is a great company and job provider. I can understand why it's been thriving for the majority of its 100+ years of operation. As a part-time employee and a college student, it certainly caters to my lifestyle and is very flexible with its scheduling, transferring, and LOA periods. Periodic raises are a plus as well as its reward systems (VPP, partnerpoints, tickets, etc). Find a store that has U-scan and gas stations; this opens more opportunities for cashiers. Best advice I can give a cashier: Do NOT take things too seriously. Honestly, it's not worth the stress. You're a cashier, for G-d's sake.
Cons
Greatly depends on the location. I've worked at multiple H-E-B's, and your mood at work will be affected by the unique clientele of that location as well as the management style. Regardless, you will find yourself frustrated occasionally by customers who go so far as to verbally abuse you and threaten to call management or corporate over petty, trivial issues. There may or may not be favoritism when it comes to promotions. Expectations are lofty and high. After working the same job for 4+ years, do you really expect me to be excited to come into work when I spend half the night doing assignments and all morning going to classes?