I have whippets, they are the long haired version.. but the only difference is in the skin and hair.
They are not as fragile as they look.
Whippets are rowdy puppies, and this is coming from a JRT owner. They are very sweet dogs with gentle natures. I was at a LHW get together this winter. There were 18 dogs there, regular whippets, whippets of long haired descent (look like normal whippets but carry the LH gene) and LHW. Many were intact young males. They all got along and played together. This-as a JRT owner-floored me.
Whippets are very athletic dogs they can jump and wiggle-over/under fences. They can run like the wind. When it comes to training they are smart dogs but aren't going to work endlessly for you (well Bounce is a freak...) they will do a few repetitions then wander away or start to shut down. They tend to be very sensitive/soft so are easily shut down.
They get very attached to their owners and some are aloof with strangers. (once again Bounce is a freak she loves everyone)
That all I can think of at the moment.