I upgraded recently from Fedora 16 to 17 using preupgrade, and I haven't had any real issues except one: slow Gnome loading
My boot times are a little slower, but not terribly (takes about 30 seconds from cold boot to login screen and with a 5400 RPM drive I suppose that isn't too bad).
The biggest problem is that Gnome Shell seems to take forever. Once I hit enter on the login screen it is 30 seconds until the actual shell loads. The system does not freeze and i can move the mouse but can't work. I took a look at systemd-analyze blame and here it is, but that doesn't have anything to do with Gnome (now, if anyone has ideas how to speed up the top two items, I am open to it)
[root@Ktech-Mobile1 Bobby]# systemd-analyze blame
7995ms fedora-storage-init.service
5989ms dkms_autoinstaller.service
4160ms proc-fs-nfsd.mount
3551ms var-lib-nfs-rpc_pipefs.mount
3468ms fedora-loadmodules.service
3224ms udev-settle.service
3151ms systemd-binfmt.service
2738ms fedora-readonly.service
2680ms media.mount
2649ms dev-mqueue.mount
2639ms udev.service
2617ms sys-kernel-debug.mount
2484ms fedora-storage-init-late.service
2482ms proc-sys-fs-binfmt_misc.mount
2367ms lvm2-monitor.service
2318ms dev-hugepages.mount
2204ms udev-trigger.service
1974ms sys-kernel-config.mount
1912ms systemd-vconsole-setup.service
1564ms systemd-tmpfiles-setup.service
1301ms systemd-remount-fs.service
1186ms home.mount
895ms nfs-server.service
832ms NetworkManager.service
765ms systemd-readahead-collect.service
757ms sshd.service
715ms systemd-sysctl.service
689ms systemd-readahead-replay.service
674ms fedora-wait-storage.service
537ms mdmonitor-takeover.service
480ms vboxdrv.service
417ms console-kit-log-system-start.service
352ms avahi-daemon.service
328ms boot.mount
247ms systemd-logind.service
245ms iptables.service
232ms ip6tables.service
229ms dbus.service
215ms auditd.service
191ms udisks2.service
187ms colord-sane.service
181ms acpid.service
178ms abrt-ccpp.service
173ms mcelog.service
164ms irqbalance.service
149ms abrt-vmcore.service
145ms systemd-user-sessions.service
115ms nfs-lock.service
113ms sm-client.service
113ms colord.service
75ms sendmail.service
73ms console-kit-daemon.service
50ms nfs-mountd.service
50ms wpa_supplicant.service
46ms rpcbind.service
37ms nfs-rquotad.service
33ms vboxballoonctrl-service.service
25ms vboxweb-service.service
25ms nfs-idmap.service
20ms accounts-daemon.service
7ms upower.service
3ms rtkit-daemon.service
2ms sys-fs-fuse-connections.mount
I also attached the Xorg log, but I couldn't see anything in there either (of course there is a good shot that I missed something since I have been looking at them for hours)