It's fun for a while, but repetitive combat and a lack of depth drag it down by the end.
BAD: Cliched storyline; combat becomes repetitive hack-and-slash; lacks originality; little depth to character classes and advancements; becomes too difficult near the end
Dungeon Siege is a massive, combat-oriented RPG game that has many redeeming qualities, but the lack of polishing of other features significantly drags it down.
When you first start playing Dungeon Siege, it is a wonder to behold, with a massive world to explore, fast-paced and frequent combat, and attractive graphics that hold up even by today's standards. While it's generally apparent from the beginning that the storyline is uninspired and cliched (peasant farmer takes up arms against invading enemy), the storyline is hardly what you'll be focusing on.
Also near the beginning, however, one of the major problems of the game is introduced. There are only four classes to choose from (nature mage, combat mage, archer, and melee fighter), and three attributes (intelligence, strength, agility; someone correct me if I'm wrong, that's what I remember). As you continue playing through the game and pick up party members (and there are plenty to choose from), the game begins to drag down and become repetitive. The persistent combat offers little variety and becomes repetitive and increasingly more difficult. In addition, it is evident that melee fighters are much more useful than any of the other classes. Archers are only useful for their range; they are significantly less powerful than melee fighters. Mages can be powerful when fully developed, but it takes a ridiculous amount of work to reach that level.
By the end of the game, all the same tricks are used over and over again as they just throw hoardes and hoardes of units at you, and the game becomes nearly impossible to beat. There are limited health potions by the end of the game, and I found it hard just to keep my characters alive, and while the game is generally linear and easy to follow, at some points I got completely lost. There is one feature I'm glad they have, though, and that's the ability to buy a pack mule which carries many of your items for you, allowing you to carry many more items than a normal RPG.
However, one of the major redeeming qualities of this game is the massive world that you have to explore. There are many side caverns to gain items from and an impressive variety of environments, ranging from festering swamps, sprawling mountainsides, forests, frozen expanses of snow, dungeons (and I have to give credit to them for creating more interesting dungeons than most RPGs have), and rolling plains.
So, while Dungeon Siege starts off fun and fast-paced, and has an excellent and varied world to explore, it eventually bogs down into repetitive hack-and-slash combat that features little depth, unbalanced classes, virtually no storyline, and fights against ridiculous odds, making the game especially difficult towards the end. Not recommended by me.