Having a poker room nearby was one of the reasons that I moved to Biloxi after Kartina. I spend about 1000 hours a year playing, and have played all of the 4 rooms now active here (Beau Rivage, IP, Golden Nugget, Hard Rock). In the beginning I spent nearly all of my time at the Beau. Lately nearly all of it is spent at the IP. For what I play (no limit Hold-em), I consider these to be the only rooms in town worth serious consideration.
My reasons for the transfer of allegiance from Beau to IP are as follows.
1) The rake/promo drop structure is much more favorable at IP. As of this writing, the Beau has a 10%, $5 max rake while IP has a 10% $4 max rake on no-limit games. Translated to my bottom line, this represents about a $2000/year difference in favor of IP. As to the promo drop, at the Beau it is $1 on (as I recall) a $20 or higher pot while at IP it is $1 on $15 and $1 on $30. So, both rooms will take $6 out of a fully raked pot, but at the IP that money is split 67/33 between house/players, while at the Beau the split is 80/20. As a result, the IP has a vastly superior range of promos -- and anyone who is not supplementing his playing income with promo money is missing a serious bet.
2) In most other regards the 2 rooms are similar. Both have (based on my experiences at over a dozen different poker rooms) above-average dealers and floor staff. Both offer free drinks (alcoholic and non-) and comped table-side food service. The cage and bathrooms are a little bit closer at the Beau than at the IP, but the difference is not significant. However, in ways that are important to me, the room at the IP has some significant advantages over that at the Beau. Specifically, at the IP the room is imbedded in a no-smoking section of the casino, while at the Beau there is a no-smoking section of slots on one (open) side and a smoking section on another (open) side that provides a bit more air pollution to one side of the room at the Beau. Also, as here are more, and more active, slots adjacent to the poker room at the Beau, there is much more noise pollution there.
3) Since I live locally and don't need a hotel room (which would be a wash if I did -- both hotels are excellent and the poker rate is about the same) the principal comp from either room is food. Both comp their buffets and several side restaurants, though the IP has a slightly better comp rate and pay-out policy. Having eaten a lot at both, I would say that, especially for someone who loves prime rib, the IP has the better buffet.
In spite of the fact that IP management has been knocking itself out finding new ways to give away the extra promo money that it collects, on almost every night the Beau is clearly the leader in terms of number of games. Both rooms will have 4-8 limit and 1-3 no-limit Hold-em games, but the Beau will usually, while the IP will very seldom, also have 2-5 no limit Hold-em and an Omaha game (limit or PLO). My guess is that there are 2 reasons for this.
First, habit -- the Beau has been #1 for a long time. The herd returns to the water hole that it knows.
Second, there is a noticeable difference in the average 1-3 game at each room. (Having said this, remember that averages fall within ranges. I've played in some very tight as well as some very loose games at the Beau, while the game I was in at the IP last night, which had very decent pot sizes for 1-3, was declared by a Beau regular to be the loosest 1-3 game he'd played in for a long time.) The average age of 1-3 players in these two rooms is probably about 10-15 years younger at the Beau. And, perhaps because the IP attracts more people who have figured out (and care about) the implications of the $4/2 vs. $5/1 rake/promo drop ratio, the IP crowd seems to be on average a bit more math/odds-oriented. So, on average, the 1-3 games at the Beau will be more ramming-jamming, with the potential for much bigger swings, than at the IP.