Space☆Dandy is an unique project within the anime industry. Japanese licensors have never been too eager about getting their shows distributed globally and the ones that got the rights had to work their connections only to have them for a limited time-frame with strict rules enforced about how to release it (including translations). Due to this the medium has probably one of the most active communities of translators and fansubbers investing their free-time to get shows localized in an alternate way (same goes for scanlating in manga). The right-holders seem to have realized the massive loss of revenue over the recent years and now supply simulcast services like Crunchyroll, Funimation, Daisuki, etc. with the new episodes (and scripts) to allow for a timely online release after airing in Japan. So along comes Dandy, licensed in multiple countries but also airing on Adult Swim, dubbed in English and premiering a couple hours before Japan - that is a surprising leap! This could pave the future for other shows being tailored at a wider audience outside of Japan. So far it is doing alright and I'm curious for a rating comparison once the last episode aired.

I haven't said anything about the show yet heh? Well, one of the reasons why the project was chosen for this kind of release is the involvement of Shinichiro Watanabe who directed Cowboy Bebop which did exceptionally well in the US. When looking at the individual credits though his involvement isn't that big technically. I don't really know that details of how it got produced but the setting bears a strong influence of American culture, intentionally or not. The obvious one is of course Dandy's style and his obsession with BooBies (a fictional Hooters) but also the references within show (Planet of the Apes, George A. Romero, etc.).
The story plays out episodic and even introduces different time lines. Due to different people being involved each episode, they all have a different feel to them (and sometimes even a new artstyle). It can range from goofy to some with actual drama. I enjoyed most of those but there were also some bad ones in there.
Space Dandy will continue it's run in the summer which will probably advance the overarching story of the show and if not... well it doesn't matter. I can't say how it's mainstream appeal is but I'm not sure if the Bebop fans for example would enjoy it (they take place in the same universe though). With proper expectation of a comedy I'd say most people will find something here just not something substantial.

As for the age old question of dub versus sub: They're actually both good. The most obvious difference is their robot companion QT which sounds a lot more feminine in the Japanese dub. A small thing is also the OP which in the Japanese version packs a lot more punch (but I think they used it later episodes for the dub too).