What are the cases in which Isomap fails to do a good job?
Here is the visualization of COIL-20 data set in t-SNE paper:



The data-set consists of images of 20 objects (clusters). In all cases provided in the paper and some cases I found on the Internet (6000 MNIST data set, slide no. 31), the quality of IsoMap (2001) is not comparable to t-SNE (2008).