Seriously, installing the SAP Gui for Java is a breeze. I went to the SWDC and downloaded a installer packed as a jar file. Once downloaded I ran the installer and it created a Mac-ified application which integrates with the Mac OS X just perfectly.
And then the problems started to kick in, not that there is anything wrong with the software, it just appears that I don't know how to configure it. Things work a little different than in the WinGui. Here is hvat you need to do:
After installing Gui for Java, run it and click the New button. It should look something like this:

Click the advanced tab and check the check-box saying user expert.... and write a connection string in the textarea like what I've done below. Remember to substitute what is between the<and > with something from reality.

After this I was able to connect just perfectly.
When running the Java version of Gui, you won't be able to use the new ABAP code editor with code-completion and syntax highlighting. I don't see this as a loss as the ABAP code completion doesn't really complete anything for me, and the syntax highlighting almost none existent when compared to Eclipse in which i used to work. I recognise the fact that a lot of ABAP'ers love and cherish the new features, so if you're a highlighting completion lover, stay clear of Java GUI 🙂

As stated earlier, the BAPI transaction works beautifully. I only use it to read documentation and as a shortcut helper to the function builder where I can perform tests. This is also the intended usage I guess.
The function builder also work OK. Btw I never use the function builder for anything else than testing RFCs and BAPIs. When I write RFCs, which I don't do very often, I use the function builder under se80 (yeah it's the same, i know).

This describes the most common problem with Gui for Java. All properties sections are totally collapsed by default and their state gets reset every time the window is re-painted. Very annoying.
If you were to right click the context node in the views context, you might expect to se a context menu giving you the relevant context manipulation choices. However this is not the case as nothing shows up! This is a complete show stopper as there is no other way to get to these functions.
There is still a way to go for SAP before they have a working client on other platforms than Windows, or at least one that can be used for development. Perhaps SAP should make a native client for Mac as well? And what about the Linux user, I quess they're left out in the cold as well.