besides the typical bashing or whining about nerfs, etc that I've already seen hundreds of, because while most hate the so-called nerfs, I haven't even noticed them so...
You're not *going* to notice the things that Shadow players have been complaining about recently until you get to end game content. The problem with Shadows, which will land you in cases of "I just died thanks to a bad RNG string", is their spikiness, which isn't anywhere close to an issue while leveling. None of the hits are big enough to really have it matter. As such, you're not *going* to notice them for another 15 levels.
Right now, the outright best tanks are Guardians: they have amazing utility and survivability, the best CD suite in the game, and are almost ludicrously simple to play. VGs are middling because they have the absolute least utility and worst CD suite but are perfectly functional otherwise (they're *slightly* more stable than Guardians but not noticeably). They're a *bit* more complex to play than Guardians thanks to having some CD reset stuff and a more complex resource schema, but it's not a big deal. Shadows are, currently, for any content where tanks are actually measured by their effectiveness, the worst: their spikiness is high enough that on a fair number of fights, you're liable to die entirely based off of RNG death and fully a quarter of their mitigation is reactive and non-scaling (i.e. self-healing) which means that its value is amazing at low incoming DPS and terrible at high incoming DPS and only helps you out if you *survive* the hits in the first place. On the plus side, they've got the best mean mitigation (not that it means much since tanking 2.0 is all about surviving spikes) and some excellent utility.
I don't mention threat or damage because it's pretty much a wash: all of the tanks do pretty much the same damage and generate the same amount of threat. One of the *only* well balanced aspects of tanks at the moment is threat/damage.