Hell and God's ways

Earlier this week, I was at a table with colleagues and the discussion came around to a new book about Hell, responding to Rob Bell's book, "Love Wins." I can't remember the author or the name of the book in rebuttal. All I recall is my colleague highlighting the argument which reinforced his understanding of Hell. So this blog is not a defense of either books, since I have not read either, but a discussion on my friend's argument. My colleague stated the argument which he agreed with was the thought that God's ways are higher than our ways--Isaiah 55:9. And so when we have a problem with God sending someone to Hell, God's ways are higher than our ways.
I have a couple of issues with this argument.
1. Using Isaiah 55:9 in this manner is an easy way out. If you don't agree with me, "well, you know God's ways are higher than our ways, so it may not sound right to you." Those who disagree with the author or my friend's view of Hell could use the same argument against them. "I know you believe that only those who accept Jesus as Lord and Savior will be saved, but God can pardon who ever he wants. You know God's ways are higher than our ways." I do not believe we can have complete understanding this side of Glory of all spiritual truths but I don't think we can simply dismiss different views with "God's ways are higher than ours."
2. What is the context of Isaiah 55:9? Isaiah 55 begins "if anyone is thirsty, come and drink." It is an invitation to come back to God. Turn from your wicked ways. Verse 7--right before the "my thoughts are above your thoughts, my ways are above your ways," states, "God will abundantly pardon." What? God's thoughts and ways are above ours.....in the context of God will abundantly pardon. It is not our way to pardon so greatly. It is not in our way to expect to be pardoned for the wrong we have done. But it is God's way. Now this is in no way near a complete exegesis of Isaiah 55. But I think we need to look at the context of a verse before we quote it to back our position. We can and should respect the Bible more than simply using it as a bunch of loosely connected Proverbs we can whip out whenever we need a defense or even a word of encouragement. God's story is much bigger than mere snippets.
So those are my thoughts on my friend's defense on his view of Hell. No, I didn't share it with him at the time. There were an awful lot of social dynamics at play and well, lets say I wasn't comfortable. But I share it with you. What is your take on Isaiah 55 and how we use verse 8-9?