With other systems, I'm pretty particular about shooters. I picked up Halo 3 and Modern Warefare 2, but I didn't pick up Blacksite Area 51 or World at War. Call of Duty 2: yes, Call of Duty 3: no. Resistance: yes, Resistance 2: no. I have The Conduit and am happy to have it, though its seen less playtime than other shooters. Nothing about it says 'finish me'. But I did play all the way through Metroid Prime 3.
As for the controls, while its a draw, its kinda a moot point. Yes, controls are a selling point. If a game controls like crap (Dark Sector) I won't pick it up. But there are plently of games that leap that hurdle. Its not the biggest leap for a game to make, just one of several.
Truth is, as long as the controls aren't borked, I'll be picking up the game. But I have this lingering doubt that I'm going to be making a complete run through. I haven't made a complete run through on any of the Halo games by myself other than ODST, and I have yet to finish Metroid Prime 1 and 2 (blasphemy, I know). So not finishing a game is not new for me... But I think most here sit in that boat.