Except for the cockpit views, he didn't compare the two games, his buddy did. I don't see what's wrong with comparing the two games. I doubt he's comparing them on a simulation level. If he had more fun playing Shift than that's cool.
As far as cockpit views, I think Shift is doing some neat things visually - desaturation, per-pixel motion blur, camera rattle. I would say Forza 3's is no slouch though, mostly due to the game running at 60fps. Seeing those Gamersyde videos (which are actually encoded at 60fps) is amazing. Shift just can't match that smoothness. I like how some cars cockpit views were tweaked for usability.
Also, while I would love to have at least a few of the things Inin0 mentioned, I would be perfectly happy with a bloated Forza 2 as well. I think that game could've really used more tracks, more cars on the grid, race types, a better career mode, and more online options. Turn 10 looks to deliver on those and them some, except for more cars on the grid, which is my biggest disappointment. The new career mode in Forza 3 sounds fantastic. So glad P2P races are back and great looking fantasy tracks (Fujimi Kaido!). All Forza 2 had for fantasy tracks was Maple Valley and New York, and those tracks suck, as did having no tracks with any real elevation changes. There's more race types this time like a proper drag racing mode. I really like the user-generated content and customization stuff in Forza, I've spent several hours just painting cars, and their taking that stuff to the next level.
This Storefront video blew my mind. Hearing the multiplayer now having a hopper system similar to Call of Duty or Halo is great news. But what's really exciting about the multiplayer is the rules editor. It's confirmed to be like Halo 3, but with even more control, which is insane and has me all giddy.
This is Halo 3's options:
http://halowiki.net/p/Gamesettings
http://halowiki.net/p/Gamesettings_Traits
Now think about having options like that, and more, but that would obviously correspond to a racing game.