Rather than posting a formal review (please check out Mitch's mid-November write-up for a deep dive) I have a few observations, one month post-upgrade.
Conversion of existing VMs from v3's format to the latest rev is required as part of the upgrade. This is a somewhat lengthy process for larger images. It works. Eventually. I had a couple false starts where a conversion was not viable upon boot; XP wouldn't get past a safe-mode start, VM tools didn't load, etc. Rather than spending hours digging into root cause, I followed the general trend of advice on the discussion boards and reconverted the original VM. The second convert seemed to do the trick; two problem XP guests, both resolved with a second conversion attempt. One additional pain: an interim upgrade required an additional VM conversion to match the upgrade rev 4.0.3540. No problems that time around.
My Debian instances all run just fine in v4, by the way.
USB connections are well managed in the new version. Very well managed. We finally got rid of our last XP laptop last week; we had retained a 5-year-old Dell for a few site-specific tasks. The XP machine was lugged around to control a number of ancient serial-connected devices around campus. Thanks to Parallels, we rounded up a handful of DB9 to USB converters to rig all the gear and had no issues with Windows drivers for our aged converters nor with Parallels' ability to recognize the devices, route USB connections, and remember preferences per external device to the appropriate Windows session on a workhorse MacBook Pro. Such a simple thing, but much joy can come from simple things.
While I still love Coherence mode, Modality mode does nothing for me. I dislike having XP's taskbar items cluttering the top of my OS X UI. Heck, that's why I like Coherence mode (or Unity mode in VMware Fusion) -- I only tend to run one XP session on top of my Mac desktop, and I like mixing and matching apps and interfaces as required. I can see where Modality works for developers or folks running many, many VM instances; it displays translucent mini-VM windows on top of your Mac desktop. Heck, I'd like to see it added to Parallels Server ... but that's another post.
The iPhone Gimmick. Yes, I've installed the Parallels iPhone app. Yes, I have used it to start and shut down VMs. From the magic of my 802.1x Wi-Fi network. Yes, the app lets me see a (small) snapshot of the VM's desktop. Yes, this is a gimmick. But I'd really like to see it working with Parallels Server in combo with VPN. And speaking of Parallels Server, stay tuned for a post or two as we wind up to a full write up as part of our Rolling Review series on VM hosts.
And finally: faster, better, stronger. Support for Pixel Shader 2, Direct X9 and hardware acceleration that takes advantage (up to 256 MB worth) of my MacBook Pro's 512MB GeForce 8600M GT may not be that useful to a nongamer, but it's nice to have if needed. Half-hour snapshot increments are useful for paranoid users with lots of drive space. And, bottom line, general performance vs. the current version of Fusion is better -- VM startup and resume times are noticeably faster, and processor intensive tasks are dramatically improved. Like most VM products running on a single-disk system, disk I/O for both products is adequate. For those who've jumped ship based on v3's somewhat rocky performance, check out the latest rev of Parallels.I spend 80% of my work life in a 100% Mac shop. I've used VM solutions from Sun, VMware, and Parallels on Apple hardware for InformationWeek. We've been a Parallels shop at my day job 'cause, frankly, it was first out with desktop and server solutions. We're much happier with the latest rev of Desktop.