I have a 125 Sprint and I absolutely love it; to paraphrase a couple of advertising slogans 'If Carlsberg did scooters...' and 'if only everything in the world was as reliable as a Vespa'.
I started out with a PX125 which was as cool as the other side of the pillow, but changing gear a million times a day in city traffic with a manual twist grip gave me godawful tendonitis in the wrist. I bought the Sprint new three and half years ago and have done around 25,000 kilometers, it hasn't missed a beat - the only thing it has needed, apart from a new back tyre, is routine servicing, which is peanuts.
Honestly, if I don't ride it for a couple of days I can't wait to get back on it. A couple of years ago some git pulled out in front of me without looking, I was thrown off and broke my collar-bone. Friends and clients all imagined I would give it up, but the 5 months I couldn't ride it was torture. And having stood for 5 months, after cranking it over for a minute or two it fired up perfectly.
I've thought about the 300, but as my riding is 95% city centre there doesn't seem much point, but I'm sure they are every bit as fun as mine.
The fact is, Piaggio have been making scooters for a long time and they haven't let the grass grow - constantly refining and upgrading. Even less emotional reviewers than me will say they are also extremely solidly made.
Maybe there are other scooters out there which are quicker or cheaper or more fuel efficient but I wouldn't swap if you paid me. When the current one finally needs replacing it'll be replaced with another. For me it's a bit like owning a Rolex or a Leica or a Lacoste shirt; people will give you all sorts of logical, well-argued reasons why there are better choices out there, but you have the quiet knowledge you are the owner of the original and genuine item.
Buy a Vespa and you won't regret it.
Anyway, I'm sure messym will be along shortly to add her two penn'orth.