Equivalent to a 28mm on 35mm format, this can easily be classified as a budget, fast wide-angle for use on m43 cameras. I currently use an Olympus E-PL1 and the lens makes a good match and is better value than Oly's almost equivalent 12mm offering which costs about 3 times as much.
I have used roughly comparable lenses in the past for other cameras, including the Olympus OM1/OM2 from the 70s, and others from Nikon and Canon for various of their film cameras and paid much higher prices for much slower lenses back in the day. For Panasonic to achieve an aperture of f2.5 in a lens this compact is quite an achievement and is partly due to the use of modern glass and lens formulations. It is probable that performance may suffer a little in comparison to that of a more complex design, but its performance is pretty good once stopped down to around f5.6-f8. Few true wide-angles will perform at an outstanding level when wide open and this is no different. If you want to pay the price for a Leica-branded design, you may get a higher level of performance and, if you were to use the lens professionally or extensively, you may be able to justify that price.
I had read reviews for this lens before purchase and most were very complimentary, if not glowing. None was very critical overall, although there were a few comments about one aspect or another within some. Performance was usually rated as very good and value generally as high. I have not used it extensively as it is partly duplicated by the kit lens, which it actually outperforms at the wider apertures and is a full stop faster. Consequently, I use it most when I need its speed or when its size and weight provides a benefit.
If you do not want the kit lens, this plus the 20mm (or possibly the 25mm Leica) with the mid-range zoom (40-150/45-200) would make a good basic system.