I read the book once, saw the 1971 version several times, saw the 2005 version once.
I think both movies have their merits, but ultimately I liked the 1971 version better. I saw the 2005 version not long after it came out. My stepmom asked me if I liked it because she wanted to take the grandkids. "Well, it's definitely a Tim Burton film," I said. And that's not a bad thing in and of itself. Nobody's gonna argue that Tim hasn't made some damn fine movies. But I felt that Tim was trying to be really, really faithful to the book and ended up just copy-pasting dialogue, songs, and whole scenes into his movie and then just went ahead and made a Tim Burton film anyway. Plus, I preferred Wilder's malicious negligence to Depp's cloud cuckoolander negligence.
The 2005 movie was faithful in lots of places where it shouldn't have been and threw in a load of back story where none was needed, and it really bogged down the movie. Prince Pondicherry's chocolate palace- unnecessary and just mildly racist enough to be squirmy. Jungle scene- too long, probably also unnecessary and please, you expect me to believe that Jacko actually did the dirty work of hacking through the jungle? I mean, if they at least lampshaded it, I could have accepted it. Telling Charlie he has to abandon his family for the factory- felt like a plot contrivance to add some conflict for Charlie and Wonka. Father backstory- good for showing where Wonka gets his fanaticism from and for explaining why he wants Charlie to abandon his family and for, well, Christopher Lee, bad for making Wonka less of a mysterious character and for also feeling like a plot contrivance to add conflict for Wonka.
I would hardly call the 1971 version a feel-good movie. Just re-watch the boat scene. Contrast it with the 2005 boat scene which if I had not seen the previous movie or read the book would have assumed was an ad for a theme park ride, although it does involve a bit of bovine S&M which is always awesome.
Yes, the 1971 version is flawed. The whole fizzy lifting drinks bit did destroy the point of Wonka looking for a child that wouldn't disobey, and did make Charlie and Grandpa Joe look like morons for not remembering the grisly fate of the last two children. The story probably wouldn't have worked in film without Wonka at first telling Charlie that he didn't win the factory after all and Charlie giving up his Gobstopper but neither the fizzy lifting drinks nor the family abandonment routes were the way to go. Maybe if Charlie and Grandpa had honestly gotten lost? But there was a good reason for substituting the geese for the squirrels. Imagine trying to accomplish the squirrel scene pre-CGI. At best it would be reminiscent of a bunch of Muppets dragging Verruca off, at worst it would be reminiscent of the BBC Zaphod.
Does the 1971 movie do the book justice? Probably not, but I don't think that was the point of the filmmakers. But the 2005 movie doesn't do it justice either.