I bought this movie because I'm an Alfred Molina fan.
Firstly, I don't think this movie is the best movie ever, however, I don't think it's as bad as people claim. For the most part I could understand the accents (I'm not from Ireland). To be fair, I do watch a lot of independent and European films so I'm kind of used to making out accents, for those who aren't, there is no English Subtitles as a previous reviewer noted. There were a couple places, however, where I couldn't understand what was said. One time was during a heart-to-heart moment between Mike Meyer's character, Pete, and Mickey... not a clue what he said even after rewinding it twice.
I thought the kids were genuine and pretty good actors; they never broke from their character, which were kids dealing with the loss of their parents. I couldn't figure out really how the parents died... AIDS, somehow Pete was involved (getting them into drugs, perhaps), not sure, so that plot line falls short. Alfred Molina plays the part of a "mad scientist," but I wouldn't really call him that. I'd say he's more of a socially awkward scientist and he does well enough at the part. There's one beautiful piece of cinematography (not a lot in this movie, unfortunately) when he's up on a hill with his telescope crying: very nice (not his crying, just the scene). There are these strange "Teletubbie" sci-fi moments where you're half expecting a big baby face in the cloud to start giggling - due to lack of any budget I'm sure.
A previous reviewer notes that when the neighbors arrive to complain about the meteor the "...main kid talks about how that started the "war of the meteor", but they won - no explanation of how." I couldn't find that scene. The neighbors do arrive to complain after they get the meteor back, but the main kid, Mickey, says that started the "battle of the meteor," but it's very clear what he means, and he explains with the scientist on their side (Alfred Molina) they shouldn't have a problem keeping it.
Overall it's a fair movie, but yes, it has its plot flaws. Just think of it as a little-independent-mind-numbing-movie and you'll probably be alright, that is, if you can understand the kid's accents :) Good luck!