Well, I'm sure there are plenty of Mont Blanc 149 reviews already, but here's another just in case not.
I got a new 149 today, Medium Nib. I already have a 146 and 4 Pelikans + random collection of other stuff. The closest pen I already had (in size) was the Laban Mento. The Mento is very similar in size if not slightly larger (but it feels lighter - dunno if it really is or not). Presentation and packaging are awesome, huge box with a bottle of Mystery Black included.
The pen looks and feels real quality, the finish is superb. It writes very smoothly (although perhaps my Pelikan M600 is a little smoother) and the flow is slighly on the wet side although I would prefer that to being slighltly too dry.
How much writing I get from a single fill will take some time to judge, i flit between pens and typically take notes rather than write pages at a time.
I was planning to buy a new bottle of Lavender Purple to use as first ink, but I see that's been withdrawn - I await its replacement.