Really lovely! Definitely worth a visit.
I came for the 1:30 tour and was told that I couldn't join because I hadn't signed up ahead of time. I would suggest getting there a bit early or calling to see what's up with the tour. I came back for the second English tour and was glad I waited for the tour - it was pretty interesting.
It's a bit difficult to get change for lighting candles, so might want to do that before you get there, if you are interested in that.
The main part of the church is filled with tourists taking pictures (etc) as if in a museum, but there is an area set aside for praying where "tourist" activities are not allowed.