I'll try and make this quick - After 2 hours and 23 minutes, I finished Portal, and I have to ask myself "did I make the right choice combining it with Portal 2?" What it comes down to is, do I believe I could have reasonably played through this game nine more times in a row?
Probably, I could have. It may may even have made for an interesting series of blog posts. Still, I think I made the right choice. Going straight into Portal 2 doesn't quite have the novelty of unnecessarily repeating the original Portal, but I'll probably enjoy it more.