In general, I consider Sense as the most polished variant of Android. Nearly everything looks better then on stock android.
But as I also had an Galaxy S2, there is no reason for me to keep the Incredible. This is not a fair comparison, but if you once get used to the speed, brilliant display and great camera of the S2, there is no need to use the Incredible S until you get it really cheap and are not willing to pay the extra money for the SGS2.
So I did not write a complete review for the Incredible S, but I want to share a few comparison photos and videos with you.
All HTC phones before the Incredible S are well known for their crappy cameras. Though HTC phones had their strengths, like the mentioned high software quality, the cameras where just rubbish. The Incredible S has been the first HTC phone with a stronger focus on the camera. And the result does not look too bad against the iPhone 4, instead some pictures of the Incredible s look better than the iPhone 4 shots. And the iPhone 4 which has been known for its good camera for quite some time. The Incredible's camera is not great, but at least average.
Incredible S video
iPhone 4 video
Comparing the video results of both phones, without going too much into detail it's a draw in my eyes. Depending on where you stop the video, you will see some parts are better on one phone and vice versa.
To sum it up: if you are looking for a phone with a very good camera, then go for a Galaxy S2, iPhone 4S or Nokia N8. If you are instead looking for a phone with a good software, the camera is not so important for you and you get a good offer (not more than 60% of the SGS2 price), then the Incredible S might be worth a try.