I really enjoyed this film, mashing together as it did a nostalgic movie about childhood with sci-fi blockbuster. It does have the feel of a classic Spielberg movie (ET, most notably), while still seeming to bring something fresh.
The child actors were great (particularly when they were pretending to act badly for their own zombie film within-a-film), the tension and pace was wonderful, and despite some plot holes a mile wide (where exactly did all the soil from that giant hole go?) it romped along at a brisk and enjoyable pace. And it featured an ELO song as a bonus - brilliant!
I do wish that J.J. Abrams would drop his obsession with lens flare though - it's getting a bit ridiculous.