'JUST' a Mercedes? What cars do your friends drive?
A Porsche is dime a dozen in some places, plus they all look the same. The Boxster is the poor mans Porsche, and personally there's just no clearly defined front or rear on it IMO.
Having said that, Porsches are good cars and having driven a Boxster S, I can say that "yes, it is a very good car", but I greatly prefer the SLK look, both interior and exterior.
I never really 'considered' other cars before getting the SLK. When I saw it in person, I thought it was just awesome. At first, I had my doubts about the 'nose job', but it was after the Geneva car show that I knew I had to upgrade from my older R170 which at the time, was my favorite car for under 100k (swiss francs). For the price, the 55 with it's folding top cannot be beaten.
Yes, for the price one could have a more powerful car, but brand new at just over 100k, this thing is as close to perfection as I can afford at the time being.
If I had unlimited funds, I might have gone with an SL65/SLR, Ferrari 360/430, but as luxurious sporty roadsters go, this beats them all hands down [

] (the Z3/Z4, Miata, S2000, Boxster and all those other cars that fit the bracket of the old and new SLK).
The above is just my personal opinion, and I do like the cars I mentioned above. They all have their cool bits, and their poorer bits, so do take what I said with a grain of salt [

]