Try some of the other threads on this. I played the beta and for about a year after release. You can solo 1-max very easily, the build system is excellent (possibly too flexible for its own good, unlike CoH you never need 2 max level tanks, you can have several builds and pay to respec them), you can use all the powers you have and macro them well to say "fire off the biggest single target attack I have recharged". Unfortunately at max level it's "raid or bust" which is what caused me to leave the game.
Crafting and artifact hunting (fishing was after my time) are also decent solo activities.
