I can understand waiting to be approved to see all the features of IPB4, but it would be nice if a few forums would be open for the public to see the basics. Just seeing the "Awaiting Approval" is frustrating.
I've been using Luminous for a while now and it is great style that my members love. They love the style and the fact that they can change the color to whatever they would like. As a webmaster, I love the fact that it is constantly updated when new versions of IPB come out. Do not hesitate to buy, you will not regret it.
I do not believe that IPS is going downhill, in fact I believe the opposite. Among all the major bulletin board platforms, I believe that the future is the best with IPS. I would not be running my boards with IPS if that was not the case. When I open a ticket, I'm pleased with the response time. I understand the weekend skeleton crew also, so I take that into consideration when looking for a response from a ticket. Sometimes somethings slip through the cracks, it happens to every company at one point.
I love the fact that they patch and update the software frequently, it is comforting to know that they are constantly working to improve and secure the software. Now I do have my gripes with how somethings are handled, but I would have that with any software that I did not write myself.
I may be in the minority here, but when I moved my website over from other software I suffered the normal loss of traffic associated with switching software. It took a little while, but after making all my appropriate SEO changes and sticking with IPB, my search traffic is now higher than it was before with more members registering and posting. I'm pleased with my organic search results with IPB. You can't just use the default IPB settings, you should take the initiative and time to change/customize settings like Matt mentioned above. That goes with any software.