>It was nice to be able to quickly get some stuff going and then realize "Oh wow, my program is slow." Then I learned how to use VBOs and shaders and eventually got a pretty good handle on how to work it all.

Unfortunately this doesn't always work. For some programs (typically small ones, not really representative of common usage) the deprecated functionality will beat out the modern functionality in performance, until you scale up. I've seen this several times with display lists in particular.

Which will typically leave newbies with the feeling that the new functionality is crappy and slow.