On HBO On Demand this month
I don't think I ever saw this when it first came out but I played it for my 4 year old and we both enjoyed it.
I think the movie holds up pretty well. The practical effects are solid, especially the backyard scenery. Sure, the stop motion effects are dated compared to today's CG effects, but it's very detailed and works well in the story.
If this movie were made today, the kids would all be models, there'd be a lot more slapstick, umpteen product references, an iphone as an iMax scene (actually, that might be kind of cool) and like another thread mentions, there would certainly be some shrunken cellphone shenanigans.... with Hollywood's recent remake/reboot frenzy this movie is sure to be revisited in some form soon....
Anyway, the HD version of this movie looks really good, this movie would be a great candidate for a new DVD/Blu ray release.