As you can understand from my rating i think Patrick Stewart is an AWESOME actor. I "met" him in the "ST:The Next Generation" series, and started appreciating his acting abilities. As a starfleet captain he perfectly transmitted authority, commanding abilities, insight and wisdom.
They choosed the PERFECT actor for that role, i think Jean-Luc Picard is the best commander EVER in a Star Trek saga. He's clearly surrounded by great actors in the series (above all Brent Spiner and Johnathan Frakes), but you can't really forget his Shakespearean theatrical experience while watching him acting on the scene. I'd say one of the reasons of the success of TNG is the actors selection and Patrick Stewart is the one that better embody the perfection of the cast.
He's one of the GREATEST actors, perfect in any kind of role!