I'm running Java 1.6 on my server right now and I like it.
Not sure what Java 7 will bring us, but I'll use it even if just for the better VM

As for the new language features, you can generally still get old code to work just fine.
Nobody is holding a gun to your head forcing you to use the new language features.

I think I will use 1.7 god i hate marketing ploys!

Java 7.0 for personal projects and experimentation because I can and I love using the latest and greatest. I used Java 6.0 since around build 40 and was very happy with its stability even then. Java 6.0 for new open source stuff I write at least until 7.0 is released and available for a bit of time. Java 1.4 for work, because that's what we have to use. I hope we've moved on to 5.0 by end of next year but I'm guessing it's not going to happen by then.

I will be using Java 6, because even though some of the faults outlined here are true the language and platform as a whole are improving significantly. One thing mentioned here is that Sun has dropped support for important things - I agree. JavaCOMM is buggy and I had to drop using it and write my own JNI bindings for Windows to access the serial port. JMF had tremendous potential, but it was never finished and fixed properly. Sun has made efforts to improve Java on the desktop, but how can Java programs truly compete when there is no access to modems/fax devices, scanners, any USB or IEEE1394 devices, cameras, MP3 players, CD/DVD burners, etc. ? (Not to mention that there still seem to be significant issues with printing.) The JOGL project has given us access to modern graphics hardware - that's a positive step. But it is still very difficult to do things like Apple's iLife package in Java. Hmm... imagine a cross-platform iLife clone in Java... The office suites are already doable and done in Java (e.g. ThinkFree) but there is still quite a bit missing.

I am rewriting some applications from Java to ancient C++. I need to support multiple platforms, and I get more of what I need in a much more stable form from C++ with a handcrafted intermediate cross-platform library and some selected of-the-shelf libraries (STLport, ACE communication framework). Unfortunately Java is heading in the completely wrong direction for my purpose. And starting with Java 5 I no longer trust Sun to get it right. They simply don't get it. They silently drop extensions (JavaComm). Others are silently put on life support (e.g. the media framework). But what pushed me over to C/C++ was the sudden outbreak of vanity language featuritis in Java 5. Sun was always bad at maintaining the existing code. They typically prefer to add new junk instead of fixing and finishing existing things. But with Java 5 they stretched it too fare. More bugs than one could shake a stick at and useless vanity features. I put some applications on hold when Java 5 came out, waiting for Java 6. But after seeing Java 6 I decided to move these applications straight from Java 1.4 to C++. I think I waited long enough for a mature Java version. With Java 6 now out, and still ten year old bugs not fixed, but yet more new gunk added, I have no choice but to revert to trusted and tried technology. In need something predictable to protect my investment in the long term. I am sik and tired of having to play catchup with Sun. I see the current fanboy discussions regarding Java 7, but I still don't see any sight of an attempt to fix existing things and get them right. Instead of a consolidation more fanboy vanity features than ever. Bah! That is nothing I want to put my money at.

On the desktop I'll be using Java 6... if Apple will support it on Tiger. If instead they will support it only on Leopard, I don't know. I don't want to force people to upgrade their o.s. only to run my applications... On the server side I think Java 6 with no problems.

6 is a disaster, from all I see 7 will be even worse.Meanwhile I'm reasonably happy with 5, and most of our customers still use 1.4 or 1.3, so that's what I use and will likely continue to use unless an opportunity to move away from Java to a language where the caretakers are less intent on destroying what they're supposed to guard comes along.