I was enjoying this quite a bit throughout. It had a level of nostalgia about it, given how many of this type of thing I read as a child, and I my expectations were not even remotely high. I just wanted a ghost-filled romp with a bit of mystery that wrapped up well.
I got everything except that last bit.
The general outline of the story is reminiscent of The Secret Garden in a few ways--we have a sickly child and his cousin, who comes from elsewhere and is unaware of the odd dynamics of the house. The main character is significantly more sympathetic than in that particular novel (thankfully!), but weird house and hidden cousin (though we are aware of him throughout) feels similar.
In addition to that, we have a new Mrs. Danvers (yet another literary reference, yes) in the aunt, who is creepy from the beginning and also a huge pain throughout. Blindness to flaws in all but the main character is a particularly annoying trait for a children's book character to have, and she has it in spades.
The uncle was a breath of fresh air and quite a sympathetic and reliable character himself, and the others in the house were at least aware that something was very wrong. I enjoyed sorting out the plot and it was creepy at times, so I was looking at a solid three star rating until the end, which pretty much doesn't wrap anything up.
I was left faintly bemused, honestly, and it wasn't a good enough read that "bemused" was at all a good thing. I've read a few books by the author and generally she does a better job wrapping up than this, so I'll certainly be trying more of hers in the future, but this one did not quite hit me right.