I wrapped up a few quests in Winterspring, but I hit Outland at 58 also. Kitty form will take some serious damage per fight (especially those darn overpowered hellboars there), but I did not die once to them. Honestly, I used bear form a lot... on the humanoids I was taking on 2-3 at a time, with very little downtime, but those boars enrage and will drain your HP... just be prepared for them, they're rough.
I'd say get there asap. I've gone at 58 on all 3 of my toons. My hunter was by far the easiest, warrior the roughest, druid was just right XD Once you start getting Outland greens it makes a world of difference in soloing. You'll notice a jump after each quest item you get. I've also looked for 'of the bandit' stuff in the AH. Some I replaced fast, others I have not.
Just heal after every fight, get ready to drink a lot, but it's more than worth it to step thru that portal ASAP.
Edited, Apr 11th 2008 1:06am by GYFFORD