1. Well it's trying to be a real stealth game.

2. It's not a fighting game. The combat is not supposed to be complex. Sneaking around is supposed to be the complex part.

I thought those things were obvious.  

Day one purchase for me. I believe this game has the biggest chances for GOTY. 

Actually I would expect it to be far easier to find a Grand Theft Auto then a Mario Sunshine. However your comparing apples to oranges. One franchise has sold probably well over fifty million copies. While Mario Sunshine sold under six million copies. I would like to give you the exact count, but the site does not have full sales data for the series. Further more the series is bargain priced. I even purchased a dual pack for the Xbox for twenty dollars.

The reality is you cannot compare the two. The sheer volume of GTA sales would defeat the comparison. I do know that linear games rarely have protracted life spans in the hands of gamers. You might find fifty hours of enjoyment playing a Mario game. However once you have dominated the game there is far less incentive to play through again. Some people love to play through games over and over, but for the crowd that sells used games. They are for more inclined to let go of a game they might not play again.

I do not think its an exaggeration to say Sandbox games have a longer home life then a linear platformer. Thus it is a stronger purchase. Sandbox games after the initial play through have no commitment. You can sit down play for a hour screwing with the NPCs, and then go do something else. Meanwhile if your playing a linear game your committing to another full play through.

Anyway the comment I made is solid by the time Montana would finish Creed. There would be a decent chance to find a used copy, or to borrow it from a friend that has played the game out. Meanwhile Assassins Creed would be a very friendly casual play to have on the shelf.

You might gather that I am stingy when it comes to my money. I would rather get one hundred hours out of a game I bought rather then fifty. I have spent more time on sandbox games then I have spent on platformers. So to me thats a better investment. Sometimes I just want to stick in Grand Theft Auto, and go postal on the city. While I haven't touched Sunshine since a month after I bought the game. I played through it completely twice, and the third time I did a speed run. Beyond that it is collecting dust.

You would think so, and yet every developer interview has claimed a heavy focus on the combat.  It also seems to be unavoidable on many missions, as we have seen in the first few walkthroughs.  So, if the combat is awful, the game will have major issues.  Again, I'll wait for more reviews.

Also, Dodece Mario games aren't very linear.  SMG even less so than most.  When you enter a level you go wherever you want.  It's not like Ratchet and Clank where you really only have 1 or maybe 2 paths available to you in each area.  You also are (according to the reviews) able to chose between 10 or 11 new galaxies many times, and play through the game however you want.   There are some linear levels, but it's not just point A to point B like you would think from the 2D Marios, and there is always an overworld to screw around in.  

That's not to say I don't agree with you.  In general, a sandbox game will have more replayability, but that doesn't make it an inherintly better purchase.  The quality of the experience obviously should mean a lot as well, and while SMG has 12 reviews and is averaging a 96.9% Assassin's Creed only has one.  So give it some time before you decide that you want to get it.