Lionheart is not a game that will be remembered fondly by those who bought it back in the day, and for good reason. It's setting was awe-inspiring - medieval Europe split asunder by a magic portal? The Spanish Inquisition leads the crusade against all things magical? The use of Fallout's intuitive SPECIAL system to create your character?
Unfortunately, none of these ideas are very well-realized, and you can literally see when Black Isle decided to pull its hands out of the development (after the very first city), and where the developers then decide to make it into a rather mindless dungeon crawler. The problem is, Lionheart doesn't have the sort of equipment necessary to be a fun dungeon crawler, or an extensive array of abilities to use against enemies. Combat becomes the main source of gameplay, and the combat isn't that great, in other words. The music is rather nice, however.
With all that in mind, if you're still interested in the setting and an adequate RPG experience to go along with it, by all means give it a go. GOG's price won't make you regret it.