I guess I’ll be the odd one out here by admitting that so far I like Lion.
I have been using it for a couple of weeks now on my 11" MBA, and it seems to suit both the machine and my workflow rather well.
I really like natural scroll- to me it feels… well, natural. I thought I’d hate the new scroll-bars, but I don’t really notice them. I love the trackpad gestures. The new versions of Mail and iChat have, to my mind, improved hugely, to the extent that so far I have replaced Postbox and Adium respectively, and find them better than those third-party apps. I don’t really have any need for Launchpad, but I can see why new users might. And I’m so glad that app-store apps now go straight there rather than cluttering up my dock!
Full-screen apps I’m loving unreservedly-especially Scrivener! On a small screen it makes a huge difference. I love that now not only can I use Scrivener’s original full-screen mode for undisturbed writing, but I can also use it full-screen when I’m working with the binder and cork board.
I only use Calendar on occasion, and it is fine for my needs so far. I have no idea why Apple chose to abandon it’s otherwise minimalist theme for some faux-leather style, which I am not a fan of, but it isn’t a big deal to me.
I can certainly see why people are generally hating the new Address Book though. I took a look at it just out of interest and it doesn’t seem as functional or easy to use as it should, but since it’s something I never use at all, it doesn’t worry me.
Mission control is taking more getting used to. I was a heavy user of Spaces in SL, and I do miss the grid structure and the static nature. But most of what I miss is the third-party app Hyperspaces, tbh. I would never have started using Spaces without it, and when I think about using Spaces in it’s default state, I can’t see Mission Control as worse, really, just very different. It will certainly involve some changes to my workflow, but I think I’ll get used to it. It will probably mean I’m more likely to set things up as I like them and then leave the machine in sleep, but that’s fine. And with the new auto resume feature even that may not be necessary.
I have no real issues with the new autosave feature either. In fact once I get used to it I think I’ll like it. But I do admit that I can see why a lot of you don’t. It’s just that for me and the way I work, it makes sense. When I’m drafting I tend to use Scrivener anyway, so ‘save as’ isn’t needed. Duplicate rather than ‘save as’ doesn’t seem very obvious, but as long as it works, I’m sure I’ll get the hang of it.
I haven’t had any crashes or slow-downs so far, so I can’t comment on whether it’s buggy or not. Word I haven’t bothered to install at all. I was looking for a reason to pretty much abandon it anyway and switch to Pages or Nisus Writer Pro, so I’m certainly in no hurry to install it, if I do at all. I’ve had so many crashes, bugs and annoyances from Word on every OS I’ve ever used that I wouldn’t blame Lion for any bugs I find there anyway 
The one thing that does really bug me is so small everyone will probably laugh at me, but… Why can’t I have my personalised folder/file icons in the Finder sidebar? I personalise most icons on my Mac, a key part of my organisational process, and now they all look the same in the sidebar! I haven’t found any solution to that at all, so if there is one anyone can tell me, I’ll be forever grateful!
I’m sorry for writing such a screed, but I do feel Lion is a good OS. I can easily see why it doesn’t suit the way some people work, and that they will either want to stick to SL or find it hard to adapt. But I see no reason, personally, to compare it to the utter nightmare that was Vista. It’s fast, runs all my apps (and Windows wouldn’t run a supposedly Windows-only app I needed that my SL mac ran fine), certainly doesn’t seem as buggy in my experience, and for me works just fine. When I had Vista it was slow, unintuitive to the extreme and generally so annoying that I would avoid using a computer at all costs. I feel very different about Lion.
I don’t pretend to be the expert user that you guys are. But I am not a newbie and depend heavily on my mac. Lion has been a bit of a shock in some ways because so many things are new or changed, but still it feels familiar, quick and easy to do what I want, and for me, that’s more than enough. 