I like that it runs very fast even when you have lots of projects in your workspace for which there are multiple builds/configurations being created - we can do this without slowing down other workflows by using our CI server's queue feature! There isn't anything really specific i dislike about Fastbuild but my biggest complaint would probably just come back around how easy they made things with their UI (it took me some time getting used). If all else fails maybe give them an email inquiry before deciding if its something thats worth trying out or not? We use Jenkins so setting one project at once doesnot slow us too much unless doing 10+ different versions simultaneously because each version has several jobs associated wihin itself due tot he way Git handles submodules etc.. This makes running tests faster than ever since everytime new code gets committed into master branch only 1 job needs updating instead 2-3 depending upon what kindof testing framework were planning to run against those changesets.