I hadn't heard of Blue Rose before. Kind of curious about the setting.
Overall, I'd describe the theme as upbeat and positive, much like the romantic fantasy novels that inspired the setting. People are fundamentally good underneath superficial differences and conflict comes when people give in to fear or ambition, seek unnatural power or are twisted and corrupted by outside forces. There is conflict and threats, but there's more of an emphasis on building bridges and finding peaceful solutions alongside the "kill all the bad guys" default, at least until an antagonist proves themselves just too ugly to be redeemed.
--Apart from humans, most of the standard races / species of D&D don't appear here. There are "vata" who are essentially elves or half-elves, aquatic humans, "night people" (pretty much half-orcs--they look scary and are often used as minions by dark powers, but aren't any more innately evil than humans). There are also the "rhydan", intelligent animals with magical powers--wolves, horses, lynx- or bobcat-like felines, and dolphins are available as PC options.
--A lot of familiar monsters do appear, with their origins usually being "corrupted by dark sorcery".
--Magic usually consists of "power from within" with more of a psychic theme. Classic "sorcery" involves twisting the natural world to your will, has a more sinister cast and is usually the preserve of villains.
--Aldea is the centre of the setting, and the default origin point for PC's. It's a good nation with a ruling class that honestly care about their subjects and use magic to provide things like universal healthcare and education--but, in a shocking twist, there is NO horrible secret that it's all powered by dead kittens or something! It's just a genuinely nice place that's kind of like Eberron in that it asks "how would moderately common magic actually affect society?" and comes up with a somewhat optimistic answer. The ruler is chosen by a magic unicorn-esque hart (I once saw it described as a "venisocracy"), and has a magic sceptre that can verify if anyone they are entrusting with power holds evil in their heart (though they can go bad afterwards). It's also explicitly queer and poly-friendly--and wow, that caused a few blown gaskets back in the day from various "I'm not bigoted, BUT--" internet personalities. The most common "get the band together" premise is presented as being a team of the queen's agents (the Sovereign's Finest), sorting out internal disputes and diplomatic issues, tracking down monsters twisted by Shadow, practitioners of dark magic, foreign threats, etc.
--Kern is the aforementioned Bad Guy Nation. Ruled by a lich king (or his lieutenants after he gets ganked between editions) who's the last survivor of the Sorcerer Kings who trashed the world in ancient times, it's very much Mordor / Saruman's Isengard. Dark satanic mills, undead, slavery, nothing too unfamiliar here.
--Jarzon is a harsh and rugged theocracy, socially restrictive, patriarchal, intolerant of magic, nonhumans and non-hetero relationships....it's basically Conservative Christian Land, presented as noble in some ways but ultimately misguided and oppressive.
--Rezea is a land of plains and nomads, with a general Roma / Native American / Mongolian feel.