Let us not forget, Coleman was an absolute jerk during the whole process. And,he was a sucky senator. Subsequent to Franken's establishment in office, he has proven himself equal to the best. Indeed, his lack of experience in elected office in general and the senate in particular is rather hard to detect.
Actually, it's the reverse, his lack of experience, both general and particular, is easy to detect: he speaks his mind and is looking out for the average guy and gal. The question is if he can remain this way when he does have lots of experience. A year ago, Franken jumped right into the confirmation of Sotomayor and easily bested the rest of the Judiciary Committee in thoughtful questions. A first test is how he does with Kagan. (I haven't paid any attention, but I would guess he passes this easily). His recent speech to the ACS is great, but the real test will be in four years when he's gearing up for re-election.