sometimes i buy from the registry, sometimes not-most times if i'm buying something with colors (linens and such) i use the registry for a guide to the preferences of the b/g.
i have to say-in some cases not sticking to the registry can be a blessing to the bride and groom. as an example we had a wedding invite this past summer, when i went to the websites for the stores i initialy thought the first one had been miscoded because the couple had no kitchen items at all-and the only plates, cups and such were all coded as only wanting 2 each (as in 2 dinner plates, 2 cereal bowl, 2 spoons, 2 forks, 2 knives...)-but this was the case with the entire registry.. now we knew both the b/g and thier immediate family realy well-and both were 'kids' (

from our perspective) who had never lived away from home, had no household items at all, were not being handed down any. these were also kids who loved to entertain with all their couple friends over for dinners and brunches...and had preexisting plans for family and friends to come stay with them for visits in what would be their future home. all i could wonder was if people would have to take turns or eat in shifts after those 2 items in each category was used and re-washed (and then what would they prepare food in-they had no pots, pans, bowls-no utensils they commonly used 'at home' to prepare food with).
found out after the fact that the 'happy couple' had 'spaced' on the fact that mom would'nt live with them and clean utensils/plates and such would always be washed and at the ready

that mom/dad 'would'nt need' all their kitchen 'stuff' and would just pass it off to them (so who needs to register for it)

and that 'that stuffs cheap, we'll just pick it up at the store when we need it'

(these are kids who are going to be on a majorly crimped one income budget while the dh finishes school-and the dw has to start re-paying student loans).
apparantly the registry choices did'nt come to light until the gifts started arriving-and the parents began to see that it was largly little chachkies, decorater items (accent pillows, vases and such the couple thought were 'so cute')-with no kitchen items (or linens for that matter) and only 2 settings of dishes (not china-standard daily dinner wear and stainless steel utensils). the parents were ultimatly thrilled to see more practical items arrive from folks who went 'off' the registry (and while the b/g were'nt thrilled at the time-when they moved into their own place and found they could'nt prepare the basic dishes they had 'at home'-and that buying all that 'stuff' was'nt as cheap as they thought/or remotely in their budget-they were appreciate of the minimal 'practical' items they received as well).