Personally, as a graphic designer, I love having constructive feedback, not just from other trained professionals within the field but people who know very little about the art form. This is a great way, I find, to improve my work.
Designers will recognise influences and understand the piece as a piece of design however this isn't always positive. Truly great design work isn't work that only appeals to other designers like some sort of In-Joke. Great design can and should be recognised by everyone. It may technically good work, but it also needs to be fit for the purpose and the consumer - and 9 times out of 10, the consumer isn't a designer.
My advice to you is, if you are genuinely interested in design, read blogs and magazines such as Creative Review just for the enjoyment and for you own taste within design. But in the main be constructive with feedback, and let the designers act upon it as they see fit.