all games are not created equal

Another random comparison.

Metal Gear Solid was a feast for the eyes when it first came out on Playstation. The graphics were almost jaw dropping for a game on that console. The concept itself was also new, and had a distinct charm about it.

Silent Hill was also new; survival horror games had never really been explored other than by the makers of the Resident Evil games. Silent Hill in contrast was darker, disturbing, and psychologically twisted, contrasting greatly with Resident Evils gore shock and jump tactic. However, Silent Hill had sub-par graphics, and let itself down on minor game play issues.

Metal Gear Solid had smooth animations, the game constantly kept itself fresh by introducing honed down accessory game play mechanics such as new weapons, additional stealth accessories, and multiple, varying, boss battles.

In contrast, Silent Hill kept along its same twisted path; the school would be grey and foggy one minute, and rusted and black for the next half. After that? Jog down to the hospital, where it begins grey and foggy, and works its way into rusty and dark... There isn't a lot of variation in the gameplay.

Nevertheless, in conclusion, its difficult to say which game is better. Sure the graphics in Silent Hill are terrible, but the use of fogging enhances the scary experience. The gameplay is someewhat bad also: The protagonist has trouble aiming and shooting weapons, and the camera locks, jolts, and refuses to move at times. Yet again, the way the camera follows your character from behind a wheelchair, or from a jaunty corner, adds to the sense that your being watched, and enhances the experience. But Metal Gear Solid just beats it for me, theres not alot of trouble with the camera, or the weapons, and I couldnt really put the game down - with Silent Hill, I could do easily - due to either being totally scared, or because I had to trek all the way through the same building for the third time...

Despite what many hardcore fans of the series may try to prove otherwise, Shattered Memories is best interpreted as a stand-alone spin-off game with no real connection the the canonical story/setting of the original games, other than some vaguely familiar characters and basic basic BASIC storyline.

These games start out the same, more or less.  Harry and his daughter Cheryl or driving and get into a car crash.  Harry goes searching for his daughter.  The similarities stop there, pretty much.

Shattered Memories makes great use of the Wii's capabilities (no, really!).  First of all, controlling the flashlight with the Wii's pointer is a treat and really helps immerse yourself into the game.  Creatures will pounce on you and latch on, and it requires you to actually shove the wiimote and nunchuk in the direction of the creatures, and it feels natural. 
My personal favorite is the implementation of the Wiimote's speaker.  Instead of a radio, Harry has a phone.  All noises from the phone come through the wiimote speaker, including calls, static, message notifications, and ringtones.  You may actually find yourself holding the wiimote to your ear without even realizing how silly you look.

The Silent Hill series always seemed to pride itself on being very psychological with it's horror (especially apparent in Silent Hill 2).  The team behind Shattered Memories know this, and they almost took the concept too literally.  Periodically through the game, you cut to therapy sessions with Dr. K, who will give you psych tests once in a while before moving on with the rest of the game.  These tests can change characters' behavior and outfit, and even change the appearance of the monsters and some graffiti and messages.

In the original Silent Hill, creatures roamed the streets and buildings.  You would fight them off with guns and melee weapons, or possibly flee if you so chose.  Occasionally, Silent Hill would transform into the "Otherworld" form, with wire meshes and bleeding walls and rusty metal forming the structure of the town.
In Shattered Memories, you encounter no enemies until you reach the Otherworld, which is actually called "Nightmares" in this game.  You do not fight.  At all.  Period.  Instead, you run and hide.  You charge through doors, topple objects to block your persuers, climb ledges, and hide under or inside of objects.  You can press down on the d-pad to look over your shoulder and see a small swarm of creatures persuing you, which really gets the adrenaline pumping.  Personally, I really really like the spirit behind this mechanic, but I do think it's very flawed.
For starters, the fact that you only encounter creatures during the nightmare sections really keeps you from being scared during any other portion of the game.  Also, when you get taken down, there's no game over, no death.  You just restart at the beginning of the section.  Finally, when you're running through these sections, there's rarely a reason to stop or observe something.  You're just constantly running til you find the exit to end the sequence, which means there's little reason to "hide" from these things.

Overall, I really enjoyed Shattered Memories, but it doesn't even begin to compare with the original.  I won't spoil the storyline, but there is a nice twist at the end of Shattered Memories worth playing for.  I really really like the spirit behind it, but the original had a much better atmosphere and much more to actually scare you with, plus it gives you more to think about than Shattered Memories does.