I was looking at the list of familiars you can obtain with the Improved Familiar feat when I noticed none of them had a stat bonus like the normal familiars did.(Example: The Cat familiar grants "Master gains a +3 bonus on Stealth checks")
Are you sacrificing a feat slot AND the bonuses familiars grant to you to have a better familiar? It isn't a huge blow but it seems that if you sacrifice a feat you shouldn't lose a bonus that is given as a base ability.
Best Answer
RAW (Rules As Written), it looks like it according to the rules for familiars and looking at improved familiar, improved familiars do not give you a bonus to skills. Not that this is a terrible thing; some of those improved familiars have super nifty abilities! They just don't give you more skill points to a skill. (Some of them could just perform the skill for you!)
However, one could argue that the improved familiars should grant skill bonuses, as per the "approximating familiars" section in the first link. This is all subject to DM approval; I doubt many of them would allow it.