I don’t use velomap but I use openmtbmap which is the same data just styled differently for offroad use. Whether or not it is any good depends a lot on where you are going as the openstreetmap data that it uses can sometimes be sparse. The UK is generally very well covered though. It you are going to do a trip abroad then you want to download a map and see if where you are going has decent track info. You could also go to openstreetmap and look at the map but not all of the tracks show on the online map so you may need to go into the editor to see everything.
Definitely try them out and see which you prefer. I used to build my own maps but these sites maps are so good I no longer bother. If you do use it then why not try adding data to openstreetmap if you find something is missing – it is super easy.
