I won't say they're so boring that I can't watch them, but I just can't sit through an entire concert. It's just not that exciting. Dancing for three or four songs are fun, but I find her moves similar and she doesn't exactly use the theatrical elements to wheel me in.
So not boring but not most entertaining. And the fact that Namie is not exactly the most interactive or the extroverted singer can make her a bit wooden doesn't help either. But if she's just shy, well, then what can you do?