schneeland
Hero
You misunderstand me, I DMed 3.5 using many sourcebooks and it was a nightmare. I never ran 3.5 using just the core books, I'm speculating that just using the core books was the only way to maintain sanity.
3.5 with the core books was indeed a solid experience (still a few odd/annoying parts, but manageable via house rules). We ran that for a number of years a enjoyed it quite a bit.
Once we added additional books, though, and some people started to look more seriously into system mastery/optimisation, the appeal was rapidly lost.