If your device is buggy or not usable on 1.5, it likely will be similar on any upgrade in software, including one of the leaks and the OTA.
Some bugs are washed out in the replacement of the OS, but some remain as well as new ones cropping up following the update.
Conversely, if your 1.5 was pretty solid and you were generally or totally satisfied with its functionality, that will quite likely be passed on to your upgrade as it seems to be quality control related as to the hardware (chips, connections, etc).
This is not 100% borne out, but there is a pattern emerging, and we noticed that pattern beginning way back when the first leak yielding posted reports from users of these forums.
Well, let's get the HTC and Verizon programmers on the job then, because that's not been my experience at all. (Although I can see how it could be other's.)
As for me, I upgraded to each leaked version as it came out. I have v3 installed, not OTA updated. These specific problems (battery, touch screen, lagginess) seem to have cropped up ONLY on version 3 leak (which, like to keep emphasizing, since it's consensus now, = OTA).
v2 leak only gave me very minor issues, the only one I can think of is that my avatar pic didn't always update itself from Facebook. Battery life was stellar (especially when idle) and most everything was nice and smooth. v3 (OTA) was another story. Stupid me, I thought it could only improve.
Frankly, I don't even remember how 1.5 was, it was so long ago... I was plenty happy with the leaks, particularly v2 - which I can't return to now.
Again, I can only speak for me, but this is my experience. When others are having the same experience, I don't see how it serves anyone to say "no big deal" or "it's all in your hardware". Better to have HTC/Verizon go into panic mode and look long and hard at these issues, I say... since it's now "official", there's no better remedy to any bugs than to have them fix it, as they should.