Has anyone with a strength build infused their +10 Claymore? I'm a bit hesitant to waste my infusing stones if the effects aren't all that great. Can you level up the infusion like you can with Titanite for normal weapon upgrades?
In Dark Souls 2 you can consider infusions and the +N upgrades as two separate properties of the weapon. For example, if you have a +10 Claymore and infuse it with lightning, you'll have a +10 Lightning Claymore. Further, you can "uninfuse" it and it'll go back to just a +10 Claymore. There's no upgrading of the infusions themselves. That said, if you infuse a less than +10 weapon, you can still continue upgrading it to +10 with titanite, and it will retain its infusion as you upgrade it.
Whether or not to infuse a weapon is another question. Each infusion does something different to the weapon. Something like Lightning will take away some of the base damage on the weapon and replace it with lightning damage. This also affects the scaling. A purely strength based character probably wouldn't want to infuse with lightning, since doing so would likely lower the scaling off of strength and add scaling for lightning (which is affected by Faith). A Strength/Faith hybrid build might do a lightning infusion, though.
There's so many combinations, and each type of infusion works differently (Raw increases base damage but lowers scaling, Mundane adds scaling based on your lowest stat, etc). My best advice would be to experiment with different types, as there's not necessarily a "right" answer (keep in mind that you can preview the changes before you actually go ahead with the infusion). It depends a ton on your build and playstyle.