Well it just came out today, so I have obviously not dealt enough with Lion to really know, but i have a few annoyances already.
I hate the new scroll bars and how they disappear, and even though you can make them always show up, I hate the removal of the arrows at the ends. I was always a fan of double arrows at both ends, but to not have them at all is stupid.
I don’t like the new Address book, as it is harder to add an entry and then add it to a group as it is on 2 different pages and takes extra steps to do so.
The death of Power PC apps completely is annoying, though only affects one app I have, which was an app that published my now playing song in iTunes to my FTP server. I will have to find a reasonable alternative.
The death of the spaces control panel. I for one use spaces all the time, and I love it. I have different screens for Final Cut Pro, Premiere Pro, After Effects and Photoshop, and could easily use the spaces control panel to pick which app showed up where, and have some apps show up everywhere, like Safari and iTunes. Now this has been taken away. At least it still remembers my old settings (though I had to turn off the auto rearranging of spaces which just confused things). I get mission control, but I would love to be able to name my spaces, and once again have real control over what apps show up where. Hopefully someone will release a 3rd party app to return this functionality. I mean I am glad it remembered my old Spaces settings, but not being able to easily change them is a real pain.
Not sure I like the new Mail. I was fine with how it was, and think it actually shows less info now than it did before, but at least the classic view is still available, so i can switch back if it really annoys me.
Launchpad is useless to me, and I have way too many apps for it, but might be nice for a novice user.
I am sure I will have more as I use it.
For a thorough review check out Ars-Technica’s Extensive Review, which you can also get in ebook or pdf format, though you will have to pay for it to get it in those formats.
EDIT:
I have some additions. I don’t like that in Finder windows the custom icons for hard drives no longer show up. I use custom hard drive icons for a reason for easy visual identification of drives, and not having this just slows things down.
I hate that the user library is now a hidden file, as I want to be able to go there if I need to easily. And the Utilities folder now requires administrator privileges to make changes, and strangely it won’t let me add myself in the info panel. Hopefully this is just a bug, because I trust myself with my own Utilities folder!
Another thing I hate. The ability to turn off the backwards scrolling requires either a Trackpad or a magic mouse! Well what if you only have a 3rd party mouse? That needs to be settable no matter what!
I find the Address book to be a major step backward, as it takes extra steps to do what it could do before. To add a new entry you must be within a group, but to add an entry to different groups, you have to click to see groups. I would rather have a 3 way window pane than a 2 way pane as it is now.
ADDITIONAL:
I don’t know if it is because I use a third party mouse driver (SteerMouse from Japan which I have used to enable a third mouse button on my EOL Microsoft Trackball Explorer, the best trackball ever made, which I used when using Shake and Color, both of which I probably won’t be using anymore) or if it is a feature of Lion, but moving the mouse no longer wakes my computer up. I have to hit the keyboard, which is just annoying! Is this a feature?