Okay, so first off i really like these models, they look and feel like they fit in with the 40k universe. However i do not think they are worth the price for 3 chaps. The only spares i have are 3 heads whereas other kits like the sternguard you get enough bits for conversions.
Then we come to the rules, these chaps are no where near as powerful as other things in the codex for example; devastators will give you more firepower at a cheaper cost and terminators will give you more melee power also cheaper (both points and $). I only use these guys simply because i love the look!
Also to get the most out of these chaps buy 2 or 3mm magnets or blutack so you can swap between all the weapon options.