Pretty good, on the whole. The need for indoor viewing for the tapirs and bears does knock the immersion back a little, but it's a good addition from a visitor and animal point of view. Bear outdoor enclosures are fantastic, and the main free flight aviary is very good as well (although I was bemused to see how close the popholes are to the path!). Tapirs fine, though by far the least Islands-y bit of Islands*; magpie aviary viewing is awkward as others have discussed but the aviary itself is fine as well.
*I almost don't want to say it, but I actually think to feel consistent with the rest of Islands the indoor viewing areas need just a little bit more of the 'immersion tat' and pointlessly named features - at the moment they're a bit more 'normal zoo' (which is not really a bad thing, but is perhaps not the intent!).