Is Wikipedia great for learning philosophy? Of course not, no better than it would be for learning math or physics.

But it's unsurpassed for learning what all the kinds of philosophy are, for getting a sense of all the stuff that's out there.

Simply because any "philosophy" intro text you buy, no matter how broad, will ignore huge swathes of it. Wikipedia really is the best place to get an initial "lay of the land" I'd say.

From there you can move onto survey texts in a particular subfield you've identified, then drill even deeper into Stanford Encyclopedia of Philosophy articles, and then make your way to primary texts.