I've had one hardcover (with a dustwrapper) book done so far - 158pp on premium lustre paper. Printed in the Netherlands, about 2 weeks turnaround, arrived by Fedex.
All neat & shipshape. The pages are glued not stitched (well what would you expect?) but they use a thick P-U glue not a cheap hot-melt. The colour printing is better than some mainstream published books. Not marvellous but plenty good enough.
I couldn't be arsed with their software (only accepts Truetype fonts) so I went the page-layout program then distill to pdf route.
I made my images CMYK to their colour profile, but I suspect it doesn't make much difference if you go with sRGB? Given that it was a 158pp book, I compressed the jpg's a bit - which made it a reasonable 2hr upload for the pages file.
Their 'standard' paper pages seem to open flatter, the 'premium' is quite stiff ... the premium lustre has a good smooth texture and looks better in that regard.
I have another book on order ...