I'm currently a lv 48 WAR and I am enjoying it sofar. I have a lv 50 WHM, SMN, BRD and DRG and Truth be told, tanking isn't too difficult, assuming you're properly geared. It's even easier for boss fights.
The 1st few dungeons can certainly be discouraging for a new tank. Despite being in full lv15 vendor gear I was still losing aggro to high lv players in sastasha who were simply doing their jobs. I'd exhaust all my enmity generating abilties, but still couldn't get or maintain agrro. Luckily the groups were understanding.
To some that may be an indicator that Tanking is not for them, nor is it worth such frustration.