I am not and never have been a cricketer myself, but as an englishman and avid sports spectator the Ashes is just about as exciting as it gets (2006 excepted!).
However (as i understand it), Test cricket is not in great health in a number of the biggest cricketing nations - T20 is great, but in my opinion it would be a shame if its continued expansion were at the expense of the longer form of the game.
As for the USA, i remember cycling back into Manhattan from Westchester County on a Sunday afternoon back in 2008 and being absolutely astounded by the number of cricket games i passed on the way....
Glenn E. wrote: Baseball is already excruciating... ~5 minutes worth of action drawn out over 3.5 hours. Cricket accomplishes the same amount of action, but it takes ~3.5
days to do it.

I have never been able to derive any real excitement from watching Baseball, but was recently recommended
this book as a good comparison of the two sports by someone who has played both professionally.
Rob C.