We ordered the standard bookcase without any extras

The bookcase itself is both a good height and depth which helps maximise the storage space available.  The space between the shelves is large, it would be useful to be able to order an additional shelf if there was a need to store smaller items.

Once built some of the shelves are fixed into place, while this reduces the option to move them around it does provide extra sturdiness.

It is worth noting that the pictures available online make the wood used in the bookcase look darker.