I was in the same exact position as you and went to the Captivate Glide from my Nokia E71. I loved that phone. I have the Skyrocket now and oftentimes miss the ease of the Glide. I can tell you the keyboard experience is not quite comparable to that of the E71 or Blackberry, seeing how the form factor is different and I've found the keys to be slighthy flat on the Glide (maybe to give a thinner look), but all in all I would say go for it.
And the Samsung Captivate Glide is a varation of the Galaxy SII not the Galaxy S as is the Epic 4G.