A bit belatedly, I've noticed and started reading this thread. I'm sorry to hear of your bad experiences with Tiger, fjdouse.
My background is that my family was amongst the first to use a Mac (128 K in 1984, etc.) and I've stuck with them. I use IRIX (and sometimes Solaris) and Windows XP (because I'm forced to...) at work, and I prefer to use Macs at home. There were times when I wondered whether a switch to Windows for my home computer would make things easier overall, although I didn't like the idea, but, after using PCs a fair amount at work, I became more and more convinced that OS X was a much better operating system and, over the years, I've become happier with my choice.
I have been quite happy with Tiger, by contrast. When I first installed it, I felt like nothing much had changed. After a little bit of usage, I started to feel like the OS was a bit "slicker," for want of a better way of putting it. Things felt a bit quicker and a bit better implemented, and I was left feeling a lot of tinkering had gone on under the hood, so perhaps some of the biggest changes were "understated" in my eyes. I have had one kernel panic so far (and even one is too many in my books, but maybe I'm being greedy
), but then I've had more in Panther. Admittedly, I've been using Panther for longer, and, also, I'd add that I've had very, very few kernel panics over the years, since starting with 10.1.
Maybe one reason I like Tiger is that I never got very excited about it or looked forward to it that much, as I was not overly excited by the keynote or descriptions on the Apple site (?). A bit like a pessimist being pleasantly surprised! I do like and use Dashboard, and I've never had problems with it. It has always been quick and I've downloaded a number of useful widgets, some of which I've used daily. I was never overly excited about Spotlight, especially as I rarely ever used the "Find" feature, but I've been fairly impressed and have used it more than I expected. It might take a second for the results to come up, but it feels very quick to me and seems to work as hoped. I haven't encountered problems with it, but have not used it that much.
By comparison, I felt a little disappointed with Panther, but still glad I got it. I rarely use(d) Exposé in the end, although I thought it looked nice. I feel like I'm the only Mac user in the world who virtually never uses it, as I am in the habit of hiding the current application when switching to something else; this keeps things in order for me, but I guess it means I also do little dragging-and-dropping, too. The thing I used most in Panther was probably "Labels." Jaguar, on the other hand, really did feel like a bigger upgrade. With regards to Safari, I think it always automatically decompressed attachments, and that was always one of the first things I turned off! It's a default which I'd like to see Apple change, for security reasons, but I don't think it was a Tiger-related issue. As far as Mail goes, I've actually been a bit happier with it, but always felt the need to run the activity viewer anyway, and so that is nothing new for me.
The rather disjointed appearance of parts of the OS is becoming an issue for me, and this is one area where I feel Apple do need to watch it a bit. I was really not a fan when Apple started using the Brushed Metal look in Panther, although I liked it waaaaaay back when QuickTime introduced it (QT 4?) as it was something a bit different. Having Brushed Metal windows in the OS just felt a bit too chunky and unwieldy. We now have Aqua, Brushed Metal, the new appearance of Mail etc. in Tiger, and the new iTunes appearance. I actually think the new iTunes interface looks quite a bit better, but it's a matter of opinion, I guess. I would prefer it if Apple made the GUI a little bit more consistent, whether it was the case that all windows had the same appearance, whether OS and application windows looked different, or whatever they decided upon. A theme manager might be a nice option, too.
I'm not meaning to deny your own experiences, only add my own two cents' worth and say my experiences have been very different indeed... Oh, errr, this post ended up a bit longer than I expected, sorry about that!