It's very much maligned from what I've been reading. It was always one of my favourites when I was a kid, and before I was clued up about the various performance differences between fighters, I could never understand why it wasn't more popular, as it's one of those aircraft that just 'looks right'. But even so, although it's not one of the glamourous A-Listers of WW2 like the Spitfire and the Mustang, and it always struggled a bit in terms of performance, in the right hands it could clearly do a lot of damage, and unlike a lot of other fighter planes conceived in the mid-thirties, it stayed in production almost until the very end of WW2.
It did feature some advanced stuff when it first appeared too; not many fighters had a retractable tail wheel in 1939, for example. And I don't think there is another aircraft that suits the big 'snarling mouth' paintjob as much as the P-40. Apparently it was the first Army aircraft ever to fly from a US Navy carrier too, so it does have a few claims to fame.
Chock