It is a good show; don't handicap it for something like this. If I handicapped it because I have to call up the dub when I first put it into the player then I never would have bought it. Because that drives me absolutely up the wall.
unfortunately, sony being sony isn't a valid excuse or reason to dubtitle a 50+ episode tv series. for myself, that is enough of a detriment to my ability to enjoy this particular anime (or any foreign film/series which gets subpar treatment), especially when dubtitles are usually glaringly obvious to me.
much like Buena Vista dubtitled their first couple Miyazaki-Ghibli releases (Kiki's Delivery Service and Totoro if i remember correctly), i didn't buy those but the imports instead. Buena Vista saw the error of their ways though, and all further Miyazaki releases received a proper subtitles script.
is it partly a personal preference in how i enjoy my anime, yes.
on the flip-side, a proper subtitle track is the responsibility of the license holder and for that license holder to simply use the dub script for the original language, that is a failure in their responsibility to the original work and disrespectful to the original work and the viewers. i will never be grateful to an anime company who licensed a hard-to-get series (which Blood+ is not; too mainstream) and who then use my gratitude as an excuse to not follow through on all their commitments.
it's an age-old question/battle i've fought against for over a decade and thankfully dubtitles have become pretty much nonexistent in the world of anime and foreign film so it is always disheartening to see cases of it crop up randomly.