The trilogy of Assassin's Creed Chronicles games have an interesting, connected story that takes place across three different eras of history. Each has it's own beautiful backdrop and stunning art style. However they are all marred by the lackluster gameplay.
The games all play most similarly to Mark of the Ninja: you have a 2.5D level with Main Objectives to complete using a combination of stealth, combat and free-running. In addition, Assassin's Creed Chronicles has a set of Helix moves which provide a powerful ability to be used until the meter is drained.
There are also a variety of Secondary Objectives to complete on each stage. All of this, combined with how you complete the stage (through non-combative stealth, combative stealth or pure combat) determines the score you receive at the end of each level.
This is where my biggest issue rises: this game rewards you for pure stealth more than the other two methods. The mainline Assassin's Creed games will rarely punish you for quietly disposing of an enemy (more often than not it actually helps a lot). While I am aware that the higher score is there to supply a challenge (and challenge it does), it feels like a failure to kill anyone. Especially when your end score determines which very useful upgrades you will be getting going forward. It meant that the part of me that wanted to complete the game for the story was constantly getting annoyed at the part of me that wanted to complete the game with the best score possible.
However, this would be the high point of the trilogy: the story. Playing through all three of the games left me with a want: to see these stories be explored in a fully 3D Assassin's Creed game. The characters were varied and a joy to learn about. The settings were beautiful (thanks in no small part to the wonderful art style) and interesting to learn about. And all three added more history to the ongoing struggles between the Assassins and Templars, striking that near perfect balance between real world events and how this secret conflict fit in to them.
Overall, if you enjoy the mainline Assassin's Creed games for the story, settings or the history they portray, then these games make for a great addition to the series and would be worth picking up. If, however, you enjoy mainline Assassin's Creed games for the gameplay, then I would say that these aren't worth picking up.
If you're coming to this with no preference then it is a beautiful game in terms of the story, characters and setting, that is held back (for me personally) by the gameplay. But if you're looking for a challenge, then this might be for you.