The plot of Drakensang is completely forgettable, but I remember being taken in and charmed by its atmosphere. It's very much a classical RPG setting. It's tone is more of the wide eyed, "Gee whiz, guys, let's go have an adventure in a brightly colored fantasy world!" variety than it is of the, "We are on a super serious, grim dark, quest to save the world with complicated character development and motives" variety. This might not appeal to everyone, but I liked it. It reminded me of an older 1980s or ealry 90s fantasy game, like King's Quest or Quest for Glory.
That said, I personally think it has an awesome combat and stat system. Probably my favorite of any 3D, Real time with Pause game. I really loved the wound system, for example. Drakensang 1 is trash mob heavy, but you can cut battle times in half by maximizing your party's wound potential, as after 4 or 5 wounds whatever you are fighting instantly dies. Plus, it's one of very few mainstream RPG that I've played in a long time where I actually had to do math in my head to plan out my characters, which is refreshing. So many modern RPGs just have simple STR for melee, INT for magic, and AGL for rogues, type systems, but Drakensang actually has slightly more complicated formulas for determining the impact of stats and skills, which creates unique situations for viable hybrid builds.
Plus, very, very, limited health potions and under powered magic, which I loved. Mages can heal in battle, but it takes them a long time and leaves them very vulnerable while they are doing it. Plus, there are probably only 10-20 potions available for sale in the entire game. You can create more with alchemy, but resources are limited there as well. Which I loved, as I always think it's cheap in games like Dragon Age where you can chug infinite health potions.
In contrast, though, River of Time is a great game all around, that builds on and improves everything about Drakensang. Plus, it's a prequel, so if you hate Drakensang, there's really no reason not to play River of Time as you won't miss anything. In fact, it might make more sense to just play River of Time as, in terms of plot, there's a character in Drakensang who is very unceremoniously killed off in a random side quest in Drakensang 1 that becomes the central character in River of Time. So playing ROT after Drakensang kind of creates a weird sense of cognitive dissonance, as your always aware that the writers kill the main character off with a shrug just to create the basis for a brief questline in Drakensang. I don't know much about the Realms of Arkania universe, so maybe this is all something that's explained more in its lore. But it does make the games very disconnected plotwise, as it's clear they weren't really planning for ROT when they wrote Drakensang.