Windows Installer was out for 4 years before I decided to give it a try. I was late to the party because I felt that MSI was too controlling and InstallShield for Windows Installer was too buggy. Eventually it matured and I was convinced to give it a try. 5 years later and I'm starting to get that same feeling about Application Virtualization. I can see the simplicity and reduced risk of deployment, yet I just haven't had the free time or need to give it a try yet. Maybe one day soon that will change.
BTW, I was looking into Thinstall the other day and something really, really concerned me. It seems that they want ISV's to pay license fee for every single seat that deploy to. That seems a radical and expensive departure from the per-developer licensing model. I can kind of understand this price structure for enterpise environments but not ISV's. I downloaded an eval copy but didn't have time to play with it. I'm also signed up for the Softricity beta but again, no time to look at it.
The really anonying part though is the tons of voicemails left by Thinstall sales reps. It seems like they would call me three times a day for 2 weeks before they got the hint I wasn't going to call them back.