Commander Dante 225 Attached to flamer squad
See the very bottom in regards to Dante, otherwise he doesn't seem worth it for what your getting overall. A second librarian might be a better choice for you, and allow you to spend more points elsewhere.
Librarian w/jumppack Blood Lance,Unleash rage 125 attached to a melta squad
Not bad, others may have thoughts on your choice of powers, or they might agree with them.
6x sanguinary priests w/ jumppacks 600pts one attached to each jumper squad
Your paying way to much for these guys. Unless you forgot to include some gear, these six should be running you no more than 450 points with their current setup.
3x Ten Man Assualt Squad w/ Flamer's 600pts
With only six flamers between them, these three squads are going to struggle to bring down most things they charge. What happens if any of these squads get charged by a walker or monstrous creature or a unit with even one weapon that ignores saves?
I would seriously rethink these squads, maybe cut down on one or two marines and get the sergeant a power weapon and meltabombs or some lightning claws.
3x Ten Man Assualt Squad w/ Melta's 630pts
Same problem as the flamer squads, only this time you have meltaguns instead of flamers. For these units I make the same suggestion, but powerfist as the upgrade. (It compliments the meltagun rather nicely.)
3x Whirlwind 270 pts
Rather strange choice, I would very much suggest swapping these out for a pair of auto/las predators or a pair of Baal's with heavy bolters (though in that case an additional 20 points need to be scrounged up.)
Land Speeder w/Heavy Flamer 50 pts
Kind of a random throw in, doesn't really help your army all that much; seems more like filler to be honest.
I would suggest dropping this and one of the flamer squads in favour of a squad of sanguinary guard. Hell you spent the points on Dante, might as well make a bit more use of his rules and slight modifications.
As things stand, you have 68 jump pack equipped models backed up by a lone heavy flamer land speeder and three whirlwinds who become less effective when the rest of your army closes in. You have little or nothing in the way of long range anti armour or infantry firepower, and your close combat units have extremely few weapons that will be able to put a dent in tough or strong enemies.
Honestly, given what your going up against this army does not feel very strong. Guard will easily be able to out-shoot you, Death Guard will laugh at the bulk of your close combat attacks thanks to their toughness, and mech orks have relatively little to fear from you due to lack of range. (They will be able to bring overwhelming numbers to you in a short amount of time.)