$.02 from a aix business partner since late 1990...
We provide a full-service application that is build to run on AIX. We started with AIX 3.1 and now have all our clients up to 5.1L. Certainly AIX has its quirks. But so do ALL other OS's. Certainly AIX has been rock solid reliable. Certainly the JFS has been a life saver making file intengrity a non-issue.
However, in these days of ever declining costs of hardware and software, even though IBM has dropped pricing on the RS6K's they still cannot come close to an X86 configuration on price.
When the RS6K started IBM used the POWER CPU. Then they introduced the PPC. Then they went back to the POWER. It has been like watching a tennis game from the sideline <-->.
Back in 1996-97 we developed our web banking suite on the AIX box. It worked well and reliable. Shortly thereafter with an interest in Linux I took a retired X86 box, stuck in a 500Mhz CPU and 512K RAM. I installed Linux on it and its its GUI system adminstrator to configure it. Actually MUCH easier than AIX even counting smit. Everything was done for me. The system came alive. I activated a mailerserver and apache and made available perl and php and mysql. Remember, that box was activated around 1998. It is still running and is still our primary mail server, file repository and web server for some of our web services. Remember, this was a RETIRED OLD P233 box.
Since then we experimented more with Linux while still continuing development on AIX. However, last year we finally replaced all our production web servers (we provide home banking and internet lending services for financial institutions) with AMD Athon XP+ based x86 SFF servers with RH 8 Linux. When we finally switched these processes over to these new platforms their performance compared to the RS6K/AIX boxes was about 10 times greater. All our customers commented on how their home banking because much more responsive. And the programming was the same.
Oh - someone mentioned AIX as the only system that can be fully recovered/rebuilt from tape... Not so. We installed a product called Storix (formerly sysback on AIX) and we made a bootable diskette or cdrom and used it to be a complete system image to tape (we use SCSI VXA drives). And not only have we tested rebuilding a disaster recovery system from tape but now when we setup a new box, we actually use the image tape to "clone" to the new machine. It even handles different disk geometry. The result is that upon completion the system reboots itself and voila`, you've got a fully function working system.
All this for a price that is AT LEAST 1/5th of what a comparable RS6K costs.
Our plan over the next 1-2 years is to move our entire product suite over to a Linux/X86 platform still using the same programming, just different hardware and OS. In fact, we're looking at the new AMD Opteron 64 bit processor.
So, that's my $.02 worth based on experience and NOT sales propaganda.
Now back to work!