I guess he's cool.
He's a great rider, quite capable as a time trialer and a climber, but not quite good enough at either to be a threat in any grand tour. How old is the guy? He's at least 26 as far as I know. I think he's too old already to develop into something resembling Armstrong calibre. When Armstrong was 26 he had already won Fleche-Wallone, 2nd in Liege-Bastogne-Liege, and had won a World Championship (to list but a few).
Although Landis' 2nd place in the Dauphine Libere (next to Lance) is impressive, it must be noted that his ability to have placed so highly in the first place was because he took about 15 minutes out of most of the other riders in a breakaway he was involved in during one of the early stages. He held to the top of the leaderboard commendably, but I personally think that it's highly doubtful we'll see that happen again. He'll have to genuinely earn placings like that in the future -- other teams won't let him get away in a long break.
It should be noted that Lance has been a team leader since he was 22. It's unfortunate for riders like Landis, but because he is currently riding as a domestique for Lance, he won't get the opportunity to assume leadership for AT LEAST another two years.
Again, he's a great rider. No Lance, but I'd say he's sixth best American (behind Armstrong, Leipheimer, Hincappie, Hamilton, and Rodriguez).