ah the ip, the poor misunderstood stepchild which gets such a bad rap. it personally holds a special place in my heart as it was my preferred hotel during my younger partying vegas days.
i think the key with the ip is to know what to expect, which i suppose is the heart of most of the negative reviews. the hotel really is for those on the cheap who are looking to party. the hotel is smack dap in the middle of the strip and room prices are almost always affordable. do not ever chose the capri rooms though. you should never have to stay in a motel like establishment in the confines of the strip, made that mistake once.
but the casino is dirtier and dingier but does have a fun vibe. the cocktail waitresses are attractive and very, very fast as there are many bars in close proximity to the tables. don't eat at the buffet (or really any of their restaurants) and your stomach will thank you. the standard deluxe room is pretty motel 6 looking compared to most of the hotels on the strip, but most rooms do have a balcony which is virtually unheard of anywhere else.
in all, an inexpensive place to shower and lay your head during the brief periods when you're not partying or gambling.