In an earlier post I mentioned in passing that Google Maps had the annoying feature that it wouldn't display more than 50 markers on a map, instead it would split them into arbitrary "pages" of 50 markers each. This applied either to displaying a KML map, or to using MyMaps (which presumably amounts to the same thing). However, I just noticed that this has changed - the map I created at Google MyMaps showing my Intergraph travels, which has eighty-something markers and was previously displayed on two pages, is now displayed in a single map with no pages (without me having changed anything).
It's not obvious whether they have done anything clever to handle larger numbers of markers, like generalizing multiple overlapping markers to a single marker when zoomed out, or whether they have just increased the number of markers which are displayed before a new page is generated (I suspect probably the latter, but haven't had a chance to play around yet to see if there is a new higher limit).
Another obvious enhancement request is to be able to reorder the list of items shown on the left of the map - apparently this can't be done at the moment, though plenty of people are requesting the feature. This can be done in Google Earth and resaved as KML, but currently there is no way of importing a KML file into MyMaps - though this seems like another obvious enhancement so I can't imagine it will be long before this is available.