Maybe Sean T. Collins thinks he can get away with his comments that "'Free Bird' sucks" by calling "Stairway to Heaven" the "greatest rock song ever" - well, not on this blog, baby.
"Free Bird" is one of the greatest American rock songs and probably the greatest "Southern Rock" song.
To start with, it's the contrast between the opening slide guitar licks - reaching for transcendence - and the driving, down-to-earth boogie of the guitar battle at the end. For me, that's part of the contradiction at the heart of great rock music: the search for something greater tied up with a recognition of the limits of what is actually possible. (My half-assed, overly-generalized theory, drawn from all the Greil Marcus and Dave Marsh books I read while in college: The great rock songs usually resolve in favor of the "search for something greater", while the great soul songs usually end up making a reconciliation with those limits).
"Free Bird"'s lyric is, I think, the weakest part of the song, but, as with lots of other rock lyrics, it gains resonance through its context. Looking at it from a cynical POV, the singer is trying to cop out of making a commitment with his lover: he's rationalizing bad behavior and (a) doesn't have the courage to stick it out or (more probably) (b) gives the same line to all the women he sleeps with. I don't think this cynical take is wrong - see "What's Your Name" - but I think it's only one aspect of what's going on. What gives it more of an emotional impact (for me, at least) is the contrast between the singer's rootlessness and the down-home boogie traditions of Skynyrd's music - the whole transcendence/limitation thing again.
One of the things that arts & culture buffs/critics don't talk about too much are the various "lifestyle" reasons people are drawn to careers as musicians/writers/actors/etc.. Or, rather, they'll make a joke about it - talking about joining a band to get girls, say - but they won't delve more deeply into the issue. Musicians will make jokes about it, too - again, see "What's Your Name" - but they don't really seem to like to talk about it either. (I'm thinking of the moment during one of the interview scenes in The Last Waltz where his band mates start to talk about some of the perks of going out on the road and Levon Helm says something like "I thought we weren't going to bring that stuff up." Which, of course, makes it kind of joke, too.) There's a tendency to treat creative artists as prophets - that is, to take what they're saying as a kind of revealed truth and ignore the personal, idiosyncratic, and potentially self-serving reasons they might be saying it.
"Self-serving" brings us back to the cynical reading of the "Free Bird" lyric, but the singer's excuse - he can't stay with her because he's a drifting bohemian and can't be tied down - is balanced with what sounds to me like a real sense of regret and, in terms of the question he asks in the opening line, real fear that the answer might be "No." It's a song lamenting the rooted life that you leave behind when you head out on the road, even while it celebrates the freedom that the road brings.
(Looking at the song in its album context, which, admittedly is not the way most people experience it, "Free Bird" takes on even greater resonance as a follow up to "Simple Man".)
Well, 600 words on "Free Bird" is enough for now, but the short version is that I think it's a really beautiful song and one of the few of those really long classic rock standards that deserve their length - it's America's "Layla".