I keep all my frequently used bookmarks categorized in folders in the Favorites/Tab bar.
Right after updating this AM, there were stutters scrolling down the list of bookmarks in each folder. Now, that has largely dissipated, but it's still a little rough when it scrolls laterally in and out of folders.
It doesn't really bother me that they've switched the Bookmarks button a sidebar-style toggle interface, but I'd prefer it didn't show up each time a new tab is opened. True sidebars don't appear or disappear without being toggled on or off.
I get that the shrinking URL (and tab) bars might be necessary on the smaller iPhone screens, but now that they've brought it to the iPad, I dislike it, mainly because a only a single tap was required to reach the URL field/buttons, Favorites bar, and Tab bar before.
Now, it takes two taps, one to make them reappear, and the second for the desired target.
The situation when tapping on the URL field, and having the keyboard pop up and obscure the bottom of the array of bookmarks is even more annoying. Tapping on a folder in the Favorites brings up a bookmark list, which then does a little animation where it centers itself and narrows to list width. To me, that's a superfluous bit of eye candy.
If they are going to the trouble of making the bookmark array dynamic, they could have at least made it so it's sized properly, and not have the captions for the bottom row of bookmarks/folders cut off by the keyboard.
None of these are show stoppers, but I'd wish they'd either tone then down, or give the user options to change how they behave.
I don't really notice much difference in tab reloading frequency compared to before.