Sorry that I don't have direct experience with the P45-150 to share, but I have tested the O40-150 and the P45-175 which both have very similar IQ to the P45-150 according to many reviews and people who have owned both.
Basically all three of the lenses fall into the "surprisingly good for the size and price" category.
Central sharpness out to 150 is good, especially if stopped down a bit. But given how small and inexpensive they are of course there are some compromises. Edge and corner sharpness is not particularly good, especially at the long end. However, for lots of shots this is irrelevant since the edges and corners are often out of focus anyway in wildlife or sports shots. I'm a landscape photographer and so I notice this corner softness for sure, but for the vast majority of users it is center sharpness that matters and all three do a good job in that department.
The other trade off is in what is sometimes called "micro-contrast" or "acuity". This is how much contrast there is in fine details rather than just the limits of resolution or "bluriness". This is what gives many images "pop". These less expensive super compact lenses don't do as well in this department, even stopped down, as a more expensive and heafty telephoto lens would. Some of this can of course be made up for in post processing.
In the end this category of lenses does great for something so small and inexpensive, I think something like the 45-150 belongs in the bag of anyone who is out hiking with their camera and is concerned about weight and size. But if you test these lenses against something like the O75-300 you will certainly see a difference in corner sharpness and overall micro-contrast when shot in the 75-150 range where these lenses overlap. But of course the O75-300 is significantly bigger and more expensive so no surprise there!
While I don't own it personally (I already have the 45-175 which covers the same range with the same IQ) in general I'd recommend the P45-150 as the best general use compact telephoto for m43 right now. Don't expect miracles, but expect what I said at the top - suprisingly good give its size and cost.
Wow, thanks for taking the time to type out such a detailed response.
All of what you've said is pretty much in line with what I'm expecting of this lens and in line with what I've been reading on review sites etc.
I'm not expecting it to blow me away in every possible way, but so long as it's a good, solid performer, I'll be happy (heck, the last time I owned a tele I DOWNgraded from a 70-200L to a Tamron 70-300 because I simply didn't use it enough to justify keeping a more expensive lens around).
But...the other day I went to shoot the eclipse...got nothing. I went to China to shoot pandas and had to use the 12-50 with the 2x DTC...not exactly ideal. I do want to get my hands on the P100-300, but it's just MASSIVE. It would take up more room and weigh more than the 3 lenses I usually travel with. Plus, I hate the way the P100-300 balances on my E-M5 without the grip (and the grip adds more unwanted weight/bulk to my travel kit, plus it's also back in Canada).
So...if the P45-150 is just as good as the O40-150R and the P45-175, I think I'm set on the 45-150.
It's just as light as the rest of them, the smallest of the bunch, the cheapest and has MOIS in case I ever decide to pick up a Pana body (the GM5 is looking mighty tempting).
