As a Haswell iMac owner and recent convert from the Apple tower lineup, I think it's important for us to recognize that there is no pretending when it comes to the difference between the iMac and the Mac Pro. Every component in the Mac Pro runs circles around its equivalent in the iMac. Many circles.
For anybody who thinks "well, the iMac is a very fast, slick machine, it's not really all that less powerful than the Mac Pro," that's just not the case at all. The iMac is a heavily compromised machine, downgraded in every aspect from a Pro machine with full-size components, suited only for the consumer and occasional prosumer.
Personally I wish I could have the Mac Pro's power, and I may upgrade to the rev 2 Mac Pro trashcan depending on how my finances go over the next year. If my finances don't allow it I do not feel like my $3,500 was wasted on my current machine, it does suffice but it is a complete and utter joke compared to the Mac Pro. And it is noticeable to me on a daily basis. Just little blips that I know wouldn't happen on the Pro, occasional jitters in intense sections of a video game, a longer-than-desired export time of a QuickTime movie, etc.
Bottom line:
If iMac fits your budget and you are a consumer, go for it.
If your budget allows for the Pro but you're not sure the extra power is worth the money, go with the Pro.
For anybody who thinks "well, the iMac is a very fast, slick machine, it's not really all that less powerful than the Mac Pro," that's just not the case at all. The iMac is a heavily compromised machine, downgraded in every aspect from a Pro machine with full-size components, suited only for the consumer and occasional prosumer.
Personally I wish I could have the Mac Pro's power, and I may upgrade to the rev 2 Mac Pro trashcan depending on how my finances go over the next year. If my finances don't allow it I do not feel like my $3,500 was wasted on my current machine, it does suffice but it is a complete and utter joke compared to the Mac Pro. And it is noticeable to me on a daily basis. Just little blips that I know wouldn't happen on the Pro, occasional jitters in intense sections of a video game, a longer-than-desired export time of a QuickTime movie, etc.
Bottom line:
If iMac fits your budget and you are a consumer, go for it.
If your budget allows for the Pro but you're not sure the extra power is worth the money, go with the Pro.