This thing has more, and more varied, batteries than I recall from any 1/6 collectible. It needs 11 button batteries of three different types placed in four different battery compartments.
I keep a fair few button batteries on-hand but I'm off to the store to get more for this fig.
The things that I like best about this fig vs the SSC are it's
slightly larger, has
slightly more accurate detailing (though I still hate the undersized light-up "eye" in the blue rectangle on the HT - it's part of R2's face,) and obviously the metal dome.
The SSC to HT improvement isn't as great as I thought it would be, though my SSC does have the rubbing alcohol wipe-down on the dome to make it more metallic/reflective and that alone hugely improves the fig.
I would argue the SSC holds up pretty well to this figure. The most obvious difference is the brighter body white and the deeper, more intense blue of the HT, which I do love. Side by side, they both look like quite convincing life-size R2s shrunken down.
And this HT R2 I think is superior to the earlier TFA version because that earlier one was a sort of pee-yellow white color. This one feels much more correct as a brighter white.