I have both PT and PO. They are very similar products at very similar prices (if you take account of the fact that PO includes a HUD whereas that's additional cost with PT).
The HUD in PO is less flexible than with PT - you can choose what stats you want to see, but not where you want to see them. This can be pretty bad if you like lots of stats at your disposal, and even with minimal stats it can be frustrating.
Comparing the 2 products side by side, I'd give PT 9/10 and PO 7.5/10. I rarely use PO these days, there is no need for both products. If PT3 is the improvement that it appears to be over PT2, I would find it very hard to find a reason to recommend PO. As far as site compatibility goes, i think that PT also has the edge, though both cover all of the main sites, so that's not really an issue.
PO I guess is slightly easier to use, but not sufficiently so to give it the edge even for a technophobe (in my opinion). There is one feature of PO that would be nice to see in PT and that is your success rate with certain hand categories that you had on the flop. For example, if after the flop you had 2 over cards, a gut shot draw, a flush draw, overpair etc etc - there's a nice table showing your profit / loss if you bet, check/folded, raised etc. Useful for showing flop hand categories that get you into trouble regularly.