In reply to DayWalker123:
Sorry, time for a slightly longer, more helpful reply now! I have a fairly close fitting one (my normal size, OK over a thin baselayer, and at a push a thin fleece too) that gets used for around town, and as a summer layer to stick on over thin layers whilst sitting drinking a coffee at the summit. It occasionally gets worn as a mid layer under a waterproof if the weather turns bad. So very much an alternative to a thick fleece - with the advantage it's more windproof.
I've also got one a size up (according to the label, although despite being the same brand and jacket, it's from a different year and I'd say it's 2 sizes up) that'll go on over everything (in my case, at the very least base layer, thickish fleece, paramo smock, and often more) as a belay jacket. It's too big to wear casually around town, but great to throw on out on the hill in bad weather.
So it really does depend what you intend to use it for - I can't imagine one jacket covering both these uses well.