from the front or slightly angled side/front, the 987 has a more aggressive appearance. there's a lot of wheel well though and that never makes a car look good! a lowered 987, especially with Techart sideskirts is very spaceman spif!
the rear end of the 987 looks thin (girly, maybe) - especially with the top up - whereas, the 986 has a thicker overall appearance. the cayman, with the sloping hard top seems to fill out the rear end (especially on side view) much better.
i agree that the sidevents need some help - especially as a mid engine car, i might think that air intake and aggressiveness would be greatly improved if the airvents stuck out more - like they do on the new 911 turbo!
i like the interior of all the new Porsche's - very refined, pure and streamlined. things previously - 911 or 986 were bulky and GM ish!!!!
as has been the discussion here before - the rear wing is just strange - but then again, german's have always had greater innate sense of function over form! it'd be great to see somebody like Techart or RUF attempt a retractable whaletale design in the place of the existing "mini-wall" that pops up
at the risk of offending some out here (which is not my intent - this is only mere observation) - i think the 987 line achieves a positioning point for Porsche that the Boxster is a comparable and competitive beast (maybe this is aided by the now existence of the Cayman with similar lines...), whereas the public may view the previous boxster as - oh boy, here we go

- the poor man's porsche.