We've stayed at Seralago a few times due to the last minute nature of some of our past trips. The rooms are so-so...really older carpet, bedding, etc. They really need to refurb their rooms. I never really felt like they were the cleanest, although I knew they were...when rooms are older, they never feel quite as clean. Lower quality towels, bedding and toiletry offerings. But overall we were fine with staying there, as we didn't spend a lot of time in our hotel.
On the plus side, when we went there was almost always free breakfast for the kids. We enjoyed the breakfast just fine. Another plus, everyone there was always really helpful and really nice!! It is really easy to get to the parks and as you have probably aready discovered, it is a really inexpensive choice! Also, the kids never noticed the lower quality that I noticed, they always had a blast! They also have family suite type rooms that have one queen and a bunkbed area. The kids thought it was fun, but defnitely not nearly Disney quality.