I find arugula to be almost like a cross between spinach and romaine lettuce, but nuttier than either of those. It's faintly bitter but it's also a little peppery in a weird way. I like baby arugula too, which is a bit more mild than the normal kind.
This Trader Joe's offering is organic, which is good I guess. It started getting goofy just a couple days after we bought it. That's a common complaint about Trader Joe's produce in particular—it goes bad quickly. I don't know if that's a testament to the fact that it really is organic or whether it's not stored at the proper temperature in the store or what.
But anyway, this stuff was great while it lasted. We made salad after salad and piled it on each sandwich we had. We even threw it on our pizza slices to help balance out the carbs and grease.