The Bikini Warriors TV series is full fanservice and humor, the special BD episode racks up the former but lowers the latter. The OVA is pretty much between the two.
Like the Special, it features unhidden nipples and quite a lot of them. Especially thanks to the second episode, they probably occupy the majority of frames. That are also two borderline-hentai sex scenes, but they're extremely short and only present in the first episode.
However, like in the Special, the humor has much lower presence here. For one, it mostly lacks the RPG parody present in the main series. Instead it largely relies on lewd humor (admittedly,
not unfitting), mostly in the "Emperor's New Clothes"-like setup of the second episode.
The Bikini Warriors OVA is a nice little thing, if you want to see the characters in their "uncensored" glory and the Special wasn't enough. As such, it's best to watch it after the main series, as an extra, just like said Special. Sadly, while the OVA is amusing enough on its own, the humor of the main series is still sorely missed.