I actually beat this a long time ago, but I played it again and felt like writing a review about it. And I did.
Tenchu: Shadow Assassins (Wii)
http://img832.imageshack.us/img832/8913/tenchushadowassassinswid.jpg
Story
Like previous Tenchu games, you play as Rikimaru and Ayame, two ninjas in service of daimyo Lord Gohda. Peace has not been completely restored since the events of the previous game. Rumors of impending war circle throughout Lord Gohda's lands. A kunoichi (female ninja) disguised as a fortune-teller kidnaps Lord Gohda's daughter, Princess Kiku, during a divination session to determine the fate of the kingdom. Ayame chases after the kunoichi while Rikimaru continues his investigation on the war rumors.
Graphics
The game was released for the Wii in 2009. While the graphics don't scream "next-gen" (err, current-gen since the next generation is arriving), the graphics aren't anything to scoff at. Some of the outdoor areas are actually quite nice. There can be a few minor hiccups--the camera might be blocked by a wall when doing a stealth kill for example--but it's generally not enough to break immersion.
http://imageshack.us/a/img801/8554/tenchu4artoftheninja200.jpg
Gameplay
The gameplay of Tenchu: Shadow Assassins was criticized as being a step in the wrong direction for the series. Previous games gave the player much more freedom in completing a stage while Shadow Assassins seems almost like a stealth rail-shooter. Rikimaru and Ayame are much more agile in previous games while in Shadow Assassins they control like ninja tanks. Rooftop exploration, a hallmark of the series, is limited and the player is mostly confined to the ground.
One run through a stage all the claims made about the game seem fairly accurate. However, there's a lot more depth than there appears to be at first glance. While there is an "right" path that the game wants you to take in a stage, there are a good number of hidden, alternative pathways and secret areas, some only accessible when using items from other stages. The items themselves add a good amount of depth to the game. There are 10 unique items to use (excluding bonus and secret items) which range from conventional ninja gear like smoke bombs and assorted throwing weapons to more unusual equipment like fishing rods and ninja cats. These items have obvious uses that the game introduces to you as well as undocumented features.
http://imageshack.us/a/img708/7928/fatkittyobservation6.jpg
It may look like animal abuse, but trust me, ninja cat can take it.
Controls
Like other Wii games released around the same time, it has the obligatory waggle controls. While the controls certainly are gimmicky, they work (for the most part). The game may fail to recognize a motion, but it recognizes most of them and it is generally only a mild inconvenience.
There are a few differences between Rikimaru and Ayame, but they okay mostly the same. Rikimaru controls like the aforementioned ninja tank, but is stronger than Ayame, i.e. he moves near the same speed when he's carrying a box or body. Ayame is speedier and feels much more like a traditional video game ninja, but is weaker than Rikimaru.
Both Azuma Clan ninjas don't move super smoothly since the control is completely digital for some reason. I don't know if it was by design or not, but it seems to work with the new approach this game takes compared to the previous ones (though I admittedly only played a few hours collectively of the first two PS1 games). The controls may not allow you to flip out like crazy slaughtering samurai left and right, but they force you to take your time and plan out your moves lest you get discovered.
http://imageshack.us/a/img843/5995/screenshotwiitenchushad.jpg
One area Shadow Assassins doesn't fail to deliver in is its stealth kills, also known as hissatsu. There is plenty of neck-snapping, slice 'n dicing, conflagration, drowning, etc. kills to please everyone. Off the top of my head, there around 30-40 unique hissatsu factoring in the item and environmental-based ones. Some hissatsus are more convincing than the others.
http://imageshack.us/a/img708/9937/drsnibvlbbvc9tcxiooakni.jpg
This is a fetish somewhere, I'm sure.
Swordplay
If unarmed, the character you're playing as prefers to flee back to the last checkpoint if discovered by an enemy. If equipped with a sword, then the character will engage the enemy in duel. The swordplay isn't very good and would have benefited from the invention of the motion plus accessory. Basically, there's an attack phase and a defense phase. During the defense phase, you have to hold the Wiimote perpendicular to the angle the enemy is attacking. After the "tenchu" bar fills up, you enter the attack phase. The game points at arrows on the enemy for you to hit for extra damage, but since the attack phase has a time limit and the Wiimote isn't very accurate in detecting where you hit, it's just easier to make random cuts until the enemy is dead or the attack phase ends.
The game seems to discourage combat. If an attack is blocked improperly, your sword takes damage. If it takes too much damage, it breaks and you flee combat. If you miss blocking an attack entirely, than you flee combat (except in unavoidable boss fights, in which case you get a total of three missed hits before you lose). The Wiimote is okay at detecting the angle you're holding the Wiimote at lower speeds, but as the game throws enemies who have much higher health and attack in a faster/higher frequency at you, you're very likely to make a mistake. You can adjust the difficulty of the sword fighting at any time through the options in the pause menu. If you don't care very much and just want to get through the sword matches, you can always "cheat" by pausing, aligning the Wiimote correctly, and then unpausing.
http://imageshack.us/a/img441/8514/tenchu4c.jpg
Audio
Unlike past games, there's no option to switch to a Japanese dub (to my memory at least). Fortunately, the English dub isn't terrible. There are a few out-of-place elements (one or two minor characters have English accents for some reason) and some of the guard dialogue when detected can get pretty annoying, but it's otherwise pretty decent.
The soundtrack is actually quite good and utilizes a variety of traditional string and woodwind instruments. The downside is that, given the lengths of the stages, the music tracks tend to repeat often.
I posted this track in the video game music topic but I'm re-posting it here as an example.
http://www.youtube.com/watch?v=eAeT3B_kZ-U
Final Thoughts
However, when judged on its own merits, Tenchu: Shadow Assassins is still a fun and solidly-made game. The main story should take around 10-20 hours. There are also 50 side missions called "assignments" for you to do as well as a hard mode of each story stage. There are also hidden map/mask pieces for you to collect in the main story stages that unlock secret items. If you really hate the motion controls that bad, there is a PSP port. I don't really know the differences between the versions other than that the PSP port has longer loading screens (and the lack of motion controls of course).