I'm nervous about the roll-out of electronic FP at DL too. The lack of park wifi basically rules out international guests from using the new system so we have to continue with the old paper version for the time being - which I hope doesn't end up with us being excluded from certain things.
I don't mind the WDW system - if you are visiting from overseas during busy periods, then you can at least ensure you get on the rides you want at some point during your visit - although as Mel points out, it was hard to use the FP+ system efficiently. We probably only used one or two a day because of difficulties booking some attractions - and sometimes we'd prebook a FP only to find out it was a walk-on and we could have used it elsewhere. I also don't like how it forces you to pre-plan your parks on any given day as we also used to be more spontaneous with where we used to visit.
DLR: 2005, 2006, 2009, 2011, 2012, 2013, 2015
HKDL: 2006 (Mar & Sept), 2011 (Apr & Dec), 2014
TDR: 2008, 2010, 2017
WDW: 2006, 2013 (Mar & Sept), 2016
DCL: 2013, 2015 (Alaska & Hawaii)