Sonic and the Black Knight is okay but not really great.
SatBK starts off with some girl running from the Black Knight. He rips open an entrance to another dimension where monsters come out and corner this mysterious girl. So she uses her magic to summon the strongest of all warriors: Sonic! Well i guess hes okay... Anyway he runs in a circle which makes the monsters disappear and then impressively catches the chili dog he threw before he went after them. He goes after the Black Knight but the girl(Merlina) stops him and explains he needs to get a sword or something to stop him and so the quest begins! You also get dumb cameos of Sonic's various friends including Tails, Knuckles, Amy, Shadow, and Blaze.
SatBK's game-play is basic all you do is shake the Wii remote and sonic swings the sword. There's no different motions or anything so all you basically do is wiggle the Wii remote as you run when enemies appear. This can be annoying because there could have combos or something cool with the sword but it does focus on speed as you only slow down to fight enemies which can get annoying as you have to slow down to swing the wii remote a few times lose your speed and start running again. There are way to speed up like using soul surge or a homing attack but it gets boring quickly. There arent many things like loops or running on walls that are popular in the older sonic games but its still fun. You also get loot at the end of the level that you equip for bonuses.
Anyway the game is repetitive as most levels are just reach the goal but there are extra missions to complete for each level such as give the towns folk rings or finish the level within a certain amount of time and there are many others. There are boss fights which are very easy except if you do them on hard which is basically impossible. Anyway the game is way too short. You have to beat a few stages before fighting Arthur where you have a plot twist and Merlina becomes the enemy. Anyway since there arent any chaos emeralds sonic turns into some golden armor hedgehog because he doesnt give up and wields Excalibur to defeat Merlina because she wont listen to Sonic good advice that a kingdom that lasts forever isnt worth it. So you defeat her and the game ends.
SatBK isn't terrible i think that they Incorporated the sword nicely and there more missions to do once you beat it. You can also play as the other Knights: Knuckes, Blaze and Shadow who can each wield weapons that you can make at Tail's store. Theres also a multiplayer and other modes that let you listen to the music character bios and even information about King Arthur and such. So there is stuff to do after beating the game but its just too short to recommend buying unless your a really big fan love the game or can get it for cheap just rent it.