It depends on the group as to whether re-enactments are fun or not really...
Like for me, the F&I stuff was great because our group's a light highland regiment (very small participation though), so our dress-code's loose and our equipment list is varied... For instance, I carried a pistol and my Irish Broadsword most of the time as opposed to a rifle... My kilt didn't match anyone else's... My shirt was handmade, and I didn't have a jacket till I was nearing the end of my time in the group (I haven't participated in 2 years).
For the Civil War, my group was terribly strict though (though large), and were anal if you wore something even slightly off what they considered "official". They could be real dicks about it actually. I wanted to wear a brimmed hat, something non-military, because of the sun and they insisted on the bummer which I liked aesthetically and in cooler temps but not at Gettysburg in July, ya know? They insisited though...
The F&I group I participated with were very casual, but OTHER groups hated us. Usually the French and Indian groups didn't mind us, but local British units or actual Blackwatch units despised us and said we weren't authentic. We simply weren't authentic to THEIR regiment, and they seemed almost offended to be told that there were light highland regiments that were considered sort of "special forces" groups.
Some people take this **** too seriously would be the point, and they can ruin the fun.
I know some WW2 re-enactors who take a nutty on the slightest thing... I know some guys in the SCA who look down on anyone who doesn't have an authentically woven piece of clothing, or who have purchased armor instead of hand-made stuff.
As with anything, some jagoffs can screw up the fun, but in my F&I experiences it was really not bad at all. most people enjoyed the "colorful" look to our group... Very hap-hazard and a variety of weapons. Even a small cannon was part of our gear.