Some additional insight: the Steam reviews may be focused primarily on technical issues, but the GOG reviews (which don't require you to own the game) look to be focused on the things that Trent mentioned. And again, most of the reviews are positive; but the few reviews that are negative seem to be focused on things that aren't necessarily relevant to the game's quality. (There's a couple positive ones that are similarly unhelpful.)
https://af.gog.com/game/baldurs_gate_siege_of_dragonspear?as=1649904300 So from me? If you like the game, write a review and tell people what you liked. If you don't like the game, write a review and tell people what you didn't like. If you like the game but think it could be better, write that review. If you don't like the game but think it could be worse, write that review. I guess what I'm saying is, if you've played the game enough to form an opinion, your opinion is valuable to the people who haven't played the game yet, and also to the people who helped create it. Good or bad, make your voices heard. I would rather see substantive criticism about the game's technical stability or writing quality or visual art style, than a series of reviews that are focused on a single NPC's character exposition, or one character's easter egg line. If you bought the game through Beamdog.com and so don't have a venue for posting your review, why not Tweet, or Facebook, or Tumble about it? Take some screenshots and put them up on Pinterest, if that's your thing. Make a mosaic out of character sprites and use them to tell the story of your time with Siege of Dragonspear. There's 3500 people playing BG:EE on Steam right now. I don't expect all of those people to stop playing just to write a review. But if you're not playing right now, and you have something to say about your experience, why not write a review to share with the world?