It's a failed adaptation, I think. I can see the potential in the ideas, but the main characters feel like a waste of time and the storytelling doesn't properly hit any beat that matters. Tomoko bought it because she'd enjoyed the manga, but was saying afterwards that the manga had been better.
It's worth talking about that manga for a bit. It's by Yoshihiro Togashi, whose other work includes YuYu Hakusho and Hunter x Hunter. He's also married to the author of Sailor Moon, so they're not pinched for pennies. Apparently he's not the most profilic or regular of manga-ka, but in fairness he's had medical problems. Level E was a short manga from 1995-1997, running only three volumes. It's about an alien called Prince Baka who's one of thousands of aliens living secretly on Earth. Prince Baka is a bit like Doctor Who in his alien knowledge and ability to outwit his enemies, but he's also a jerk who's only interested in tormenting everyone around him. This was quite funny.
This is a nifty idea, so it's worth looking at why it doesn't work in the anime. I think, fundamentally, the main cast don't work dramatically. They're observing stories rather than really being part of them, oe else they don't have satisfying motivations driving their actions.
I don't mind Prince Baka being a jerk. In fact, I wanted him to be far more evil. He doesn't cause any trouble worth remembering and you don't really care whether he's around or not. Prince Baka's absence tends to make for a better episode. I'd call that a massive warning flag to say "this character isn't being used properly".
Prince Baka's supporting cast tend to be even more dull, alas. He has some bodyguards, who are basically the Men in Black. They get angry a lot and they don't like him, but I didn't give a damn about them or about what they thought. Unfortunately we meet them a lot. There are also a couple of humans who acquire Prince Baka as a flatmate. They're a bit more engaging, especially the girl, but they're also absent more often than not as the show dumps them to tell random one-off stories with other protagonists.
However the clearest indication that this show is misfiring comes at the end of ep.10. A mermaid alien is her race's last survivor, with her sisters having been sold into slavery and killed. She'd been being used as a murder weapon. She finally finds her freedom and, at the very end of the episode, swims off into the sea and finds some other mermaids... and it's not moving. It doesn't touch you emotionally. This is impossible. How can you tell that story, with that ending, and yet have it fall flat?
There's also a tonal mismatch between realistic art and outrageous stories. The latter demanded more flamboyance in the former, I think. We needed more vavoom. The artists needed to let their hair down. Characters have fury tantrums and scream at each other in scenes that could have been amusing, yet we have fairly stiff art.
This show doesn't have a clue. You could stuff, mount it and sell it to an exhibition of the unclued. That said, though, there are some saving graces.
The theme song (Cold Finger Girl) is awesome and I don't even mind the Engrish "sit down" at the end. (In Japanese, "SI" is pronounced "SHI".) Ironically, the vowel she says perfectly.
The stories are quite a miscellaneous bunch and some have cool ideas. The mermaid with the liar-killing frog tongue is both a scary and a tragic idea, since she has no control over her instincts and will kill anyone who's lying to her. It's hard to imagine anyone befriending her, because you only need to tell one little white lie ("your hair looks great like that") and suddenly your skull's been skewered. There's a version of Parasyte. Then there's the female-only species whose queen falls in love at first sight with their life partner... and then makes that partner's species extinct. One race or the other must die out.
There's wacky fortean stuff. There's a beautiful teacher who's also a cold-blooded extraterrestrial assassin who'd slaughter babies if the price was right. (She's mellowing.) All that's good.
There's also one good set of protagonists in the Colour Rangers. These are five primary school boys who get chosen by Prince Baka to become superheroes and fight evil. They come alive as people in a way that none of the other anime's characters do, so I tended to like their episodes best. They're childish, but that's because they're children. There's also a funny bit where they discover that their teacher is an alien assassin and try to hire her to murder Prince Baka. Their relationship with that teacher is genuinely interesting, I think.
This isn't a terrible show. It's perfectly competent on a superficial level that will be enough for a lot of viewers. It has lots of SF ideas. It has some good individual stories, although that doesn't necessarily translate into good episodes. It also doesn't help that the show keeps abandoning one set of protagonists for another bunch of mugs, so for instance I didn't much like Yukitaka (Prince Baka's roommate) but I still wasn't delighted when the show forgot about him for seven episodes straight. The mermaid episode probably works best, since it's played the straightest and doesn't have Prince Baka in it.
One can understand how the original manga might well have been good... but it'll be equally clear that the anime must then have made a hash of the adaptation process.