I am sure if you lurk around online photography forums, you will find certain assumptions on the inferiority of using smaller sensor systems such as Olympus Micro Four Thirds system, in comparison against APS-C or Full Frame cameras. While most of the claims were generally true to a certain extent, in several cases the fact has been stretched and pulled to serve the biased opinion of certain measurebators and camera bashers.
So here is a list of popular myths about Olympus Micro Four Thirds system:
1) Poor low light shooting, can't use high ISO.
I am fairly happy with images I obtain from my E-M5 and E-PL5 up to ISO6,400. In fact the high ISO images were better on the newer E-M1, with noticeable improvements in noise control and detail retention.
2) Inability to create shallow depth of field (blur background)
While it is true that the larger the sensor size the shallow the depth of field will be, I did not find any issue creating shallow depth of field for my shots. Using lenses such as 25mm F1.8 and 45mm F1.8 helped me to achieve blurred background, and the great thing about Olympus lenses, they are already very sharp wide open, and you can take advantage of shooting at F1.8 without compromising detail loss.
3) It is harder to hold and steady smaller cameras, with bigger DSLR providing better handling
I admit coming from a DSLR usage for many years (E-520 and E-5), the E-M5 seemed rather small, and not as comfortable to hold in the beginning. All it took was just a few shooting sessions to readjust myself and I never looked back. You just have to change the way you hold the camera. Since it is much lighter, you do not have to spend too much effort stabilizing it. That 5-Axis Image Stabilization, once you have experienced how it helped to keep your shots steady, it is difficult to shoot with another camera without it! Only Olympus users will fully understand this.
4) Smaller sensor has limited dynamic range
Technology is getting better and better, and I do not find myself in a situation where dynamic range limitation would destroy my shot. In fact, in comparison to APS-C sensors, the dynamic range is on par (I have tried a handful of recent APS-C DSLR models from various brands). However, I must admit though, full frame cameras do have that extra bit of flexibility, retaining details from highlights especially. To work around this limitation on my Olympus cameras, in situations of extremely harsh lighting condition, I would choose to underexpose the image to preserve the highlight, and in post processing I would lift up the shadows. The shadow detail retention on Olympus cameras is quite good actually.
5) Smaller cameras like OM-D are just for enthusiasts or hobbysts, not for professional or serious use.
6) DSLR has much more reliable autofocus
Not entirely true. In Single Autofocus mode, Olympus OM-D and PEN cameras are actually fast enough to challenge even the most expensive DSLR cameras out there. Yes, in terms of AF tracking Olympus cameras are still admittedly behind, but hey, E-M1 has made a significant improvement and surely things will get better and better. If the continuous autofocus tracking on Olympus camera is on par or surpassing the competition, I don't think there are many more points left to attack Olympus.
7) You need super high megapixel cameras to achieve super sharp images
Higher megapixels do equal better resolution and better fine detail reproduction, but that much extra megapixels are meaningless if you do not have equally capable lenses to resolve all that resolution. On the other hand, even a slight error (miss focus, camera shake, lens imperfections eg corner softness, chromatic aberration) will be amplified and be more destructive to your final image output. Olympus system took care of this by having high performing optics in the M.Zuiko lenses, and the application of 5-Axis Image Stabilization that has been highly acclaimed thus far.
8) Fuji/Canon/Nikon/whatever other cameras have great colors.
Personal choice, and preferences. I personally like what I see from Olympus cameras. People have always asked me what I did in post processing to get the colors they see on images on my blog. I do not know why it is so hard for people to believe that I did not do much post processing at all and the colors you see are almost identical to what came out straight from the camera.
All images were taken with Olympus OM-D E-M5 and PEN E-PL5, with M.Zuiko lenses 25mm F1.8, 45mm F1.8, Olympus 9mm F8 fisheye body cap lens, and the Panasonic 14mm F2.5 lens.
Shallow depth of field achieved by 45mm F1.8 lens. Creamy, smooth, buttery bokeh, shooting at F1.8 wide open, yet the lens is super sharp.