Hi Star10, I moved from Eircom for phone+broadband and Sky for TV to a UPC bundle for all three, last year as soon as it became available in my area. Never looked back.
On the negative side, I would say UPC's TV service is definitely clunkier than Sky, with a couple of bad limitations, although it also has a couple of great features that Sky didn't have. My absolute favourite is the ability to program forward/back buttons to jump separate amounts in a recorded program. Set it to 30 seconds backward, for when you daydreamed and need to go back, and five minutes forward -- you'd be amazed how many TV stations have ad breaks exactly five minutes long. Bliss! never have to see an ad on a recorded program again. (EDIT: Sorry - just noticed you already have UPC TV, presumably digital, so you already know all this).
UPC broadband is incomparably better than Eircom. I had Eircom's "up to 8Mb" broadband, which was actually 2.5 Mbps -- something they never showed the slightest inclination to either diagnose or fix. With UPC I get 60Mbps. Don't always get 100% of that speed, but not far off, and it is very reliable. In particular, latency and jitter are reliably very low, so I get ************************* VoIP.
The phone service is fine, main difference being €6 line rental per month instead of €25. Overall package price for me came down from about €110/month with Eircom+Sky to €76 with UPC. Recently I changed the UPC phone package slightly (to take advantage of cheaper mobile calls, which are the only thing I don't already get free from my VoIP provider). UPC kindly knocked another tenner a month off the bill for a 12 month contract extension, so now €66/month all in.
In terms of cables, there is a single coaxial cable coming into your house with UPC. They have a set top box for TV, and a separate cable modem for broadband plus phone. So there is a splitter which splits the coax into separate connections for TV and modem. There is no particularly messy cabling.