Dragonspear is probably Beamdog's best writing. I know that isn't saying much since their EE content for 1 and 2 were both kinda lackluster. Not insulting or bad, just forgettable. But Dragonspear is pretty nice, and helps fill in the gaps between the first and second games instead of just a quick narrator scene. It also very fantastically helps fix any narrative inconsistencies too, so that it explains why Minsc and Jaheira are with you in Waukeen's Promenade in Shadows of Amn, as well as why Imoen is now a multiclass, regardless of your decisions in the first game (assuming you didn't let Xzar kill Jaheira and that you didn't help Edwin kill Dynaheir).
My biggest gripe is Glint. I don't like him as a character. As a gay man myself, he feels like extremely poor representation.

The dungeons in the first half of Dragonspear are annoying slogs through waves of copy-pasted enemies that are easily dispatched with charges of the numerous wands of fire you never used in Tales of Sword Coast. But after the halfway point, especially starting with the Wyvern cave, Dragonspear really picks up and becomes a joy to play through.
It's also extremely linear, even moreso than Throne of Bhaal, which can be annoying and makes it easy to feel like you've missed content by progressing forwards when you didn't mean to.
All in all, if you like baldur's gate for the combat and the tactics, save your money and don't bother with Dragonspear. But if you're here for the narrative and want something that helps bridge the awkward gap in the two games, Dragonspear is a good addition.