Okay, I do NOT want to get into a Dolphin/Konqueror **** contest here. I've been using Konqueror as my one and only file manager since 2006, first in KDE 3.x and now in KDE 4.x. What I want to know is twofold: 1) what advantages does Dolphin have over Konqueror (because frankly I can't see any) and 2) Since Konqueror is now using Dolphin as a Kpart, is there any particular reason why we're not getting that same functionality in Konqueror? This is not an invitation to flamewar; this is a serious question that's been bugging me for almost a year.

I'm not sure Dolphin can do things that Konqueror can't but iirc the purpose of Dolphin was to provide a more focused file manager that had better usability then Konqueror. K was considered a bit overpowering/complex for newer users.

Could you elaborate on what features Dolphin has that Konqueror doesn't? You can request those features be added to K with a post on Brainstorm forum.

As far as I am aware the only thing Dolphin has that konqueror doesn't is the breadcrumb bar (which would not be possible for a web browser), the information panel (which is somewhat redundant since konqueror can use kparts), and the simple strigi search bar (which makes searches easier). In KDE 4.6 Dolphin will have the faceted search panel, but I do not know if that will be in konqueror or not.

The point of Dolphin isn't what Dolphin has, it is what it doesn't have: all of the web browser UI components, all the controls for kparts, and anywhere near as many menu items. This loses functionality but makes the program much simpler to use.

Okay, what's the Strigi search bar and what does it do?

if you use strigi to index your drive then the search bar is a gui to search the index

Settings -> Toolbars Shown -> Search toolbar.

Of course you probably need to enable strigi
systemsettings -> workspace appearance and behavior -> desktop search -> enable nepomuk & enable strigi

Okay... so it can do searches. So can Konqueror. What's the big deal with Strigi, anyway?

Strigi allows for full-text indexing and searching of the files on your hard drive, as well as keeping track of connections between files, where files came from, who or what they are associated with, and so on. Unfortunately not all the features are available to users and there are still some performance and stability issues that need to be worked out.

So basically a better search. I'll have to try it next time I need to search for something (which is almost never, I know where my files are).

So, to sum up:
the only reason to switch to Dolphin if you are already comfortable with Konqueror is because Dolphin has a different form factor that better lends to file management and is lighter on resources. Otherwise, if you are more comfortable using Konqueror for everything there is little reason not to use it.