Not too difficult to get to from Minsk. Try to organize a taxi for about $60 to $85 if you can. It will be most comfortable and reliable with least hassle.
The castle itself has good guided tours and is in good condition with knowledgable guides. Electronic guides are also available. In winter it is cold, very, very cold! Even some of the displays in the tower wer frozen over!
We stayed in the hotel which is actually situated inside the castle and quite modern. The restaurant downstairs is very good for where you are, in the middle of Belarus. You will find something you like on the menu with international wines and local unfiltered beer on tap. All at a reasonable price.
As noted in the title, the service isn't that great but if you made it this deep into Belarus you will be ok with it. The most annoying thing we found was that they turn the lift off at 6pm and with little kids and a room on the fourth floor it really begs the question... why?
I've put up a blog about our weekend there with many more details and photos. Check it out here.
I hope you make it to this attraction, it is well worth the effort!