I actually really enjoyed this game a lot, although it's easy to spot where the issues are. It made the famous mistake of trying to appeal to everyone and completely failed in the process. Retro fans disliked the complete change in atmosphere and tone, while modern fans were somehow under the assumption that this was an open-ended game, and disliked its linearity, as well as its difficulty. I think two things caused this: GRIN shot themselves in the foot by making Bionic Commando Rearmed (unofficial HG101 Game of 2008) so awesome, so the change was made incredibly apparent, and it had the unfortunate situation of releasing next to Infamous and Prototype, two other games that satiated action gamers in ways that Bionic Commando didn't.
Personally, I'd like to think of this as this generation's PS2 Shinobi, another 3D revival from about six years back that also emerged to middling reception. Both have their own fair set of issues - the pits and checkpoints in Shinobi, the load times in Bionic Commando, the repetitive level designs in both of them - but the core mechanics are just so damned fantastic that, for me, at least, it completely overshadowed any of its other issues. For Shinobi, it was the air dashing and wall running; for Bionic Commando, it's (obviously) the swinging. It doesn't really feel like the older games, but there was never any way it could in 3D. So much of the platform swinging is automatic that it loses that aspect, but it more than makes up for it with its application in combat.
Any of the major battles are made much more exciting when you're surrounded and start getting pelted up bullets, when you can leap off the nearest cliff, turn around in mid-air, latch on to something (hopefully) and slowly regain some health while firing what few enemies you can see. It is, in practice, a variation of the cover system that's been popularized by Gears of War, but infinitely more interesting because it can be used almost anywhere, without having to duck behind designer-placed obstacles. It also makes important use of vertical space and the ability to traverse it quickly, greatly enhancing any strategic combat options.
And for me, latching onto an enemy, reeling in so I slam into them and send myself flying backwards into the air, while spraying fire towards any other enemies - well, that's just as awesome as the first time you launched an enemy into the air and juggled them with bullets in Devil May Cry. It has the same exact impact as not only looking cool, but serving a important function in the game itself.
A few weeks after its release, Gamestop dropped the price to $20, although it's back hovering about the $40 mark now. That'll probably drop again come the holidays, which hopefully will convince more people to give it a go. I know this is another one of those games that's going to be showing up in "LTTP" threads for years to come, and maybe it's only in time that it'll get the respect it deserves.