Pros
The "prestige" associated with the H&M brand within the fashion industry. The compensation is above what most other retailers are willing to pay. Pretty good benefits. The 25% discount is good if you like H&M clothing.
Cons
The work environment is horrible. Morale at most stores is consistently low (I travel to different stores quite often) and store management is often times burnt out. There is an unreasonable expectation when it comes to the workload. Everybody is expected to constantly push for positive results, an expectation most employers have, but with H&M the expectation is tenfold. The company has eliminated quite a few positions without notice, demoted people without notice, all in an effort to save money. There is an almost cult-like mentality when it comes to senior management: you're either 110% H&M or we'll find a way to get rid of you. Job security is nonexistent. It's easy to lose your job with this company.