Even with sights (you need a pusher), you can assemble a slide rather quickly. I have the Brownell's slides. The funniest part of hte videos about slides is them trying to get the firing-pin-channel liner. Not sure if Brownell's manf's them oversized or what, but they just drop in.
Second most complex is the firing pin assembly. Still not that hard.
That damned frame. I HATE assembling frames in comparison. LOL.