I agree with other comments that Sykes is a bit of a frustrating one. He does go through the motions at times and obviously doesn't contribute enough in terms of goals/assists (a criticism that applies to most of our midfield, mind)
That said, I think he's comfortably our most skilful player (possibly one of two or three players in our current squad that can beat a man), has a good work rate, and - contrary to Scotchegg's assertion that he 'chokes' - performs consistently well in big matches (West Ham, Newcastle, Playoff final, this year's playoffs).
If teams like Ipswich (with arguably the best manager in the league in Cook) are genuinely willing to pay c£300k for him then to me that suggests he's got more about him than many posters on here suggest.
Henry is a strange one. His goal record for the club is very good. He's knows how to find the back of the net. That said, when he plays, the whole team's form seems to mirror his. When he's playing well, we look great, when he's not, we generally look pretty crap. With his age and apparent physical decline in mind, now probably wouldn't be a bad time to cash in.