They're not bad; interior detail is kind of lacking. What kind of Blackhawk are you wanting to build?
MH-60K - You'll need the Cobra Company Detail set to get the nose right.
MH-60G - The kit is good for a late 80s/early 90s MH-60G. (ie - there's no FLIR, MH-60Gs had 'em, HH-60Gs didn't) These days, the (all redesignated to) HH-60Gs carry a lot more sensors. The main cabin .50 M2s show up at airshows and I've seen pix of them mounted on the two-tone brown MH-60Gs of ODS. These days I don't think they're hardly ever used. Do a search for "Pave Hawk" in this forum and you'l find that Salbando has posted a lot of helpful info about HH-60Gs and posted pix over at aircraftresourcecenter.com. Also, look for posts by Mogwa as he works with Army UH-60s
UH-60 kit - Can't comment - I've never built it.
Depending how accurate or detailed you wank your Backhawk to be, you'll also need Eduard detail sets. Over on aircraftresourcecenter.com, there's a lot of articles from people who've built Hawks (Bob Silva and Davide Olivati's MH-60Ks are good examples).
Right now, I've got two on my to-build shelf, an MH-60K and the MH-60G kit. I'll put some extra time and effort into the Kilo but stick with an OOB Pave Hawk (I've got the 1/35th version going on so that's where all my Pave Hawk attention is focused at right now)