It's overall a great article. I'd disagree with some points, but then again, I don't finish games
I'd say that 90% of the work is in the first 10%, though. Hardest to create something when you have nothing to start it off from, but after you get some momentum, it's a lot easier. But if you don't have a good plan, you're going to be spending a lot of time fine-tuning it.
Disclaimer: Any sarcasm in my posts will not be mentioned as that would ruin the purpose. It is assumed that the reader is intelligent enough to tell the difference between what is sarcasm and what is not.
I personally think that if you got this cool engine in your head, it's easy to just whip it out and make it.. After that you have all the boring bits like fixing inevitable glitches.
From personal experience, I'd agree with Will. My FableQuest project kicked up pretty nicely in the beginning, but once I got far enough along for playtesting, fixing bugs and other glitches took up the vast majority of my time. ;
That's not to say that starting the game in the first place isn't tough as well - it really can be if you're tight on workable ideas.