Compared to the non Blu-ray supporting iHAS322, the iHES208 is a little off the pace when it comes to dealing with DVD content. When you combine this with the fact that the Blu-ray supporting drive is more expensive, I would suggest that if you've got the room that you look at buying a standalone DVD-ROM drive like the iHAS322 if this drive is going into your main PC.
This will do a few things; first and foremost the biggest benefit is that a drive like the iHAS322 will just be a bit quicker all round when it comes to working with DVDs. Equally important, if not more so, would be the fact that you're not placing more load than you need to the more expansive Blu-ray drive.
With DVD-ROM drives being so cheap, motherboards offering us a large amount of SATA connections and in most cases easily supporting two ROM drives, it's not only a small investment, but a wise one.
Of course, if the iHES208 is going into something like a HTPC, the chances are you probably already have a DVD player for movies. The chances are also high as well that the drive itself won't get the same amount of usage as one sitting in your main machine.
For the most part, though, iHES208 performance is good when it comes to DVDs and when it comes to Blu-rays it's fantastic with the biggest bonus being that the drive of course supports the technology.
While it's fine to replace your current DVD drive with the iHES208, unless you really need to I would suggest that you just keep what your currently using installed to work alongside this drive.
Since a DVD drive comes in at less than $30 and the IHES208 at around $110, you're only really going to buy one if you intend to watch Blu-rays. For that, this drive is fantastic, especially when you accompany it with AnyDVD HD to unlock some pesky Blu-ray features.
If you're going to watch Blu-rays, this is a fantastic product. If you're not, it's essentially an overpriced DVD drive. Why you would be looking at something like this without the intention to use its Blu-ray capabilities is beyond me.