No doubt about the smartphone tablets good points about res and bit rate. I'm not sure what Netflix ,Hulu, Amazon ,etc streaming resolution/ bit rate is for phone /tablet today probably 480p both may be higher over wifi than telco also. but some smartphones and Pads can handle 1080p
and a lot of their panels have long had native resolution much higher than 1080p .
Netflix is rolling out 1080p support for both smartphones and tablets soon it wasn't the hardware it was Netflix apps.I'm sure iTunes ,Hulu and Amazon will follow YT probably has it for them already .
while they are not driving a big panel they can stream1080p HD just fine if they receive it ,they will soon. none the less 1080p is same number of pixels (resolution if you will ) regardless of panel size but even ancient P4 with HD video card can do 1080p also for low level Android type CPU in a Roku or BD player or smart TV. Playback of 1080p + 5.1 / 7.1 audio is no big deal for CPU anymore . Editing and encoding /archiving audio/video ofc is more CPU intensive . I'm sure 5.1 HDMI/maybe Wi Fi audio support will not be long on phones some tablets have it already.
You are right Celeron 847 will work for HD HTPC playback they can do it with atom cpu also. The first Gen Roku HD-XR 1080p Box had a .PNX*8935 400 MHZ single core chip I would prefer at least the i3 for maybe some thing other than just HDTV playback ,Maybe DVD Shrink or something like that for archiving or making backup of DVD or also running WMC (which can in itself be at times slow with windows overhead on a weak chip) another consideration is that that NUC CPU are embedded parts and cannot be changed for future upgrade path maybe 4K someday which the i3/i5 should handle OK even if OP wants to burn or archive BD I don't know about a Celeron mobile doing that I haven't even tried that with desktop no BD dive in this one yet ?
If OP just wants to watch steaming Netflix or Amazon then a Roku or other device will be a lot cheaper and work fine . OP never mentioned what he wanted to do with it.
if he wants some PC function also the NUC i3/i5 is better. Celeron 847 is to slow for gen PC use if he does more than e mail ,some net surfing Y tube Netflix etc.
I got the impression he wanted it to do double duty also is he going to attach ODD ? or discrete video although I don't know what type of laptop GPU would be good
I'm assuming he will keep intel HD .
The Celeron 847 vs i3 3217U overall are not that far apart at CPU BOSS
but are very far apart on individual and Pasmark benchmarks but if you are only streaming,playing media,light browser ,email (not to many open tabs) no multi task you are right Celeron is fine. anything more than that the i3/i5 are better solutions .
I stream WMC media from HDD's or other content from web around the house on wi fi and might be doing encoding editing and watching a movie maybe netflix or maybe posting here on the other screen all at once while also streaming WMC media from my daily driver all at the same time but it is 4 core desktop and does double duty just fine .
ofc there are two other desktops +PS3 and 2 smartphones on the lan so there is plenty of cpu available.
For HT BD and Netflix I use PS3 or can send WMC media or other content to PS3 to TV I like to archive some movies (dual layer DVD's) into WMC in a DVD 9 format others in DVD 5 depends on the movie lenght and content so for me at least a Celeron would not work . Maybe OP will come back and we can ask him what he wants to do with it? I think NUC are a little expensive for what they can do but are quite remarkable compared to an old P4XX or Athlon 64 XX box OTOH the small form factor is sometimes nice if you need it.
My first box was a 386sx33 with math co processor ,EGA graphics and 14.4 modem 2 megs of ram,100MB hdd on BBS before anybody ever heard of AOL . long time ago it ran DOS 2.0 and win 3.0/3.1 .