Let us (me
) how you get on with it. I've been looking at the oly or that one to have a small walk around birding set. Some say the oly is somewhat better image quality, but overpriced as you said.
I guess I can give you my opinion on that also.
I used mine for a couple of months and sold it two days ago.
IMO is a very good lens optically speaking, it's quite sharp wide open. I compared it with a Nikkor 300mm F4 AF-S and a 300mm F4 ED AIS side by side on the G5, it's actually sharper than both of them wide open, and the AIS really doesn't stand a chance.
Ok, in all fairness, the primes are a stop faster wide open and they do keep up stopped down to F/5.6. Nevertheless I found that impressive, the 100-300 is a small, cheap, plastic body lens, basically a consumer lens, the fact that it held it's own against a 300 F4 is very respectable.
The OIS worked fine too, I was able to get slighly over 3 stops from it.
Now, not everything is so good, AF is a pain, plain and simple, I don't know if it's the lens itself or it's the CDAF system fault as this was the only lens I used on m4/3. Most will say it's CDAF fault, I don't know.
On static subjects it worked fine, photos are sharp and correctly focused, but anything moving and I get better acuracy manual focusing my scope with trap focus.
I'm not saying you can't get good moving subject photos, but keepers rate is low, I had a lot of almost focused images, but very few critically sharp images.
In short, it's a good lens because it's cheap, with good image quality, has a 600mm FOV, and is very small and easy to carry in the field. But is let down for it's AF system for action photos. At least this was my experience with my sample