The photo paper I have at the moment is -
HP 'Everyday photo paper'. It is semi-gloss (I think I called it semi-matt earlier) for inkjet. It is 170g/m2.
The gloss paper at the printers was also about 170g/m2. It reminded me of the stuff used on 'up marked' magazine covers.
There is a knack to using a household iron. I struggled bravely on with it for a couple of months. It is probably the most intensive part of the process. The iron needs to be moved around. But not by 'skating' pick it up and place it back down. Overlapping where it has just been. Apply plenty of pressure.
Make sure the edges of the PCB are de burred as if left in place it may stop the iron putting enough pressure near the edges leading to poor adhesion.
Pre heating the PCB first with the iron is also a good move. I do have a tutorial posted up at the projectdalek site (I'm a mod there shhhh) If you want I could post it in a new topic? It was written based on my first efforts.
My very first attempt, which was to build a prototype voice mod on, went perfectly, 100% even, using the TT on photo paper. Previously, and at much expense, I had fought with the 'press n peel blue'. This was very hit and miss with regards to the PnP crinkling at the edges during transfer which smeared the traces or left gaps. This may be purely down to not having the knack but I was up and down the temperature scale trying to cure this issue without success.
Local printers are also more likely to let you use your photo paper in their machines as the PnP needs to be attached to a normal bit of paper to act as a carrier to ensure it passes through the printer without mishap. Also if your not using the whole sheet it's pricey or just fiddly cutting out the piece you need to stick to the carrier. with photo paper you can be a bit wasteful for the price.
Obviously I have moved on with the conversion and use of a laminator but the basics are all the same.
To date I have made, in the 2 years since my first efforts, around 40 PCB's and probably a few more than that. I have a page set up now, waiting to print, with about 8 PCB patterns on it.

regards
Fenris